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RANKL binds to tnfrsf11b/opg and to tnfrsf11a/rank. Osteoclast differentiation and activation factor. augments the ability of dendritic cells to stimulate naive t-cell proliferation. May be an important regulator of interactions between t-cells and dendritic cells and may play a role in the regulation of the t-cell-dependent immune response. sRANKL may also play an important role in enhanced bone-resorption in humoral hypercalcemia of malignancy.

IGFBP6 plays a role in lipoprotein assembly and dietary cholesterol absorption. in addition to its acyltransferase activity, it may act as a ligase. may provide cholesteryl esters for lipoprotein secretion from hepatocytes and intestinal mucosa.

Insulin-like Growth Factor-Binding Protein 7 (IGFBP7) is a member of the IGFBP family. IGFBP family members are all cysteine rich proteins with conserved cysteine and have an IGFBP domain, a Kazal-like domain and an Ig-like C2-type domain. IGFBP7 is expressed in a broad range of normal human tissues and it mostly shows reduced expression in cancer cell lines of prostate, breast, colon, and lung origin. IGFBP7 has a role in skeletal myogenesis by binding to IGF in a manner which inhibits IGF induced differentiation of skeletal myoblasts, without disturbing IGF induced proliferation. Moreover, IGFBP7 suppresses growth and colony formation of prostate and breast cancer cell lines via an IGF independent mechanism, which triggers a delay in the G1 phase of the cell cycle, and increased apoptosis.

Complement C1q Tumor Necrosis Factor-Related Protein 5 (C1QTNF5) encodes a short-chain collagen which is expressed mainly in sub-retinal pigment epithelium, ciliary epithelium and adipose tissue. C1QTNF5 is increased in mtDNA-depleted myocytes and stimulates the phosphorylation of AMP activated protein kinase. C1QTNF5 takespart in the adhesion of the retinal pigment epithelium (RPE) to the Bruch Membrane. Mutations in C1QTNF5 have been associated with late-onset retinal degeneration.

CDNF is a member of the ARMET family and acts as a trophic factor for dopamine neurons. CDNF inhibits the 6-hydroxydopamine (6-OHDA)-induced degeneration of dopaminergic neurons. When CDNF controlled after 6-OHDA-lesioning, it reestablishes the dopaminergic function and inhibits the degeneration of dopaminergic neurons in substantia nigra. CDNF is universally expressed in neuronal and non-neuronal tissues. The highest levels in the brain are found in the optic nerve and corpus callosum.

IGFBP6 plays a role in lipoprotein assembly and dietary cholesterol absorption. in addition to its acyltransferase activity, it may act as a ligase. may provide cholesteryl esters for lipoprotein secretion from hepatocytes and intestinal mucosa.

CFI cleaves and inactivates C3b and C4b. CFI is inactive without a cofactor such as the soluble factor H and C4b binding protein. CFI cleaves the alpha-peptide chain of C3b and C4b when these binds1 of the cofactors. This cleavage inactivates all of the complement activating functions of these proteins producing iC3b and iC4b.CFI cleaves the alpha chain of C3b twice and this releases a small fragment called C3f. CFI can cleave iC3b releasing C3c from C3dg in the presence of CR1.C4b is cleaved rapidly at 2 sites separating C4c from C4d.

NELL2 is expressed in large quantities in neural tissues and has a significant role in the development of neural tissues. In addition, NELL protein has six epidermal growth factor (EGF)-like repeat domains which plays a part in calcium binding.

Complement Factor Properdin (CFP) which is a plasma glycoprotein, is a positive regulator of the alternative complement pathway of the innate immune system. CFP binds and stabilizes the C3- and C5-convertase enzyme complexes in a feedback loop that eventually ends with formation of the membrane attack complex and lysis of the target cell. Mutations in CFP lead to 2 forms of properdin deficiency that cause high susceptibility to meningococcal infections.

GDF15 is part of the TGF-Beta superfamily which is involved in regulating inflammatory and apoptotic pathways in injured tissues and throughout disease processes. GDF15 is most abundant in the liver. Its expression in liver can be considerably up-regulated in during injury of organs such as liver, kidney, heart and lung. GDF-15 promotes proliferation or growth arrest and differentiation due to differences in cellular differentiation. GDF15 prevents apoptosis in cerebellar granule neurons by activating Akt and inhibiting endogenously active ERK. GDF15 is a novel autocrine/endocrine factor that antagonizes the hypertrophic response and loss of ventricular performance.

Killer-cell immunoglobulin-like receptors (KIRs), are a family of cell surface glycoproteins found on Natural Killer (NK) Cells, which are important cells of the immune system. They control the killing function of these cells by interacting with MHC class I molecules, which are expressed on all cell types. This interaction allows them to identify virally infected cells or tumor cells that have a distinctive low level of Class I MHC on their surface. The majority of KIRs are inhibitory, which means that their recognition of MHC suppresses the cytotoxic activity of their NK cell. Only a limited number of KIRs have the capacity to activate cells. The KIR genes are found in a cluster on chromosome 19q13.4 within the 1 Mb leukocyte receptor complex (LRC). KIR molecules are extremely polymorphic, meaning their gene sequences differ significantly between individuals, so that different individuals have different arrays/repertoires of KIR genes. The KIR proteins are categorized by the number of extracellular immunoglobulin domains (2D or 3D) and by whether they have a long (L) or short (S) cytoplasmic domain. KIR proteins with the long cytoplasmic domain transduce inhibitory signals upon ligand binding via an immune tyrosine-based inhibitory motif (ITIM). Whereas KIR proteins with the short cytoplasmic domain lack the ITIM motif and instead associate with the TYRO protein tyrosine kinase binding protein to transduce activating signals. KIR2DL3 is an inhibitory Killer Cell Ig-like Receptor (KIR, previously called p58 KIR, cl-6, NKAT2 or KIR-K7), which recognizes class I MHC molecules (HLA-Cw1, -Cw3, -Cw7, and Cw8). KIR2DL3 inhibits the activity of NK cells thus preventing cell lysis.

The somatomedins, or insulin-like growth factors (IGFs), comprise a family of peptides that play important roles in mammalian growth and development. IGF1 mediates many of the growth-promoting effects of growth hormone (GH; MIM 139250). Early studies showed that growth hormone did not directly stimulate the incorporation of sulfate into cartilage, but rather acted through a serum factor, termed 'sulfation factor,' which later became known as 'somatomedin' (Daughaday et al., 1972). Three main somatomedins have been characterized: somatomedin C (IGF1), somatomedin A (IGF2; MIM 147470), and somatomedin B (MIM 193190) (Rotwein, 1986; Rosenfeld, 2003).

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.

Epidermal growth factor has a profound effect on the differentiation of specific cells in vivo and is a potent mitogenic factor for a variety of cultured cells of both ectodermal and mesodermal origin. The EGF precursor is believed to exist as a membrane-bound molecule which is proteolytically cleaved to generate the 53-amino acid peptide hormone that stimulates cells to divide. EGF stimulates the growth of various epidermal and epithelial tissues in vivo and in vitro and of some fibroblasts in cell culture. Long EGF is a recombinant analog of Human EGF developed as a replacement for use in therapeutic cell culture applications as a like-for-like supplement for Recombinant Human or native EGF. It includes the Human EGF amino acid sequence plus a 53 amino acid N-terminal extension peptide.

CDNF is a member of the ARMET family and acts as a trophic factor for neurons. CDNF inhibits the (6-OHDA)-induced degeneration of neurons. When CDNF controlled after 6-OHDA-lesioning, it reestablishes the function and inhibits the degeneration of neurons in substantia nigra. CDNF is universally expressed in neuronal and non-neuronal tissues. The highest levels in the brain are found in the optic nerve and corpus callosum.

The somatomedins, or insulin-like growth factors (IGFs), comprise a family of peptides that play important roles in mammalian growth and development. IGF1 mediates many of the growth-promoting effects of growth hormone (GH; MIM 139250). Early studies showed that growth hormone did not directly stimulate the incorporation of sulfate into cartilage, but rather acted through a serum factor, termed 'sulfation factor,' which later became known as 'somatomedin' (Daughaday et al., 1972). Three main somatomedins have been characterized: somatomedin C (IGF1), somatomedin A (IGF2; MIM 147470), and somatomedin B (MIM 193190) (Rotwein, 1986; Rosenfeld, 2003).

GDNF promotes the survival and differentiation of neurons in culture, and is able to prevent apoptosis of motor neurons induced by axotomy. The encoded protein is processed to a mature secreted form that exists as a homodimer. The mature form of the protein is a ligand for the product of the RET (rearranged during transfection) protooncogene. In addition to the transcript encoding GDNF, two additional alternative transcripts encoding distinct proteins, referred to as astrocyte-derived trophic factors, have also been described. Mutations in this gene may be associated with Hirschsprung disease.
GDNF enhances survival and morphological differentiation of neurons and increases their high-affinity uptake.

The fasting-induced adipose factor (FIAF, ANGPTL4, PGAR, HFARP) was identified as an adipocytokine up-regulated by fasting, by peroxisome proliferator-activated receptor agonists, and by hypoxia. At the protein level, in human and mouse blood plasma, FIAF was found to be present both as a native protein and in a truncated form. Differentiation of mouse 3T3-L1 adipocytes was associated with the production of truncated FIAF, whereas in human white adipose tissue and SGBS adipocytes, only the native FIAF could be detected. Interestingly, the truncated FIAF was produced by human liver.
Experimental data suggest that FIAF is mainly presented in human blood plasma in a truncated form (FIAF-S2), whose level is increased by fenofibrate treatment. Levels of both truncated and native FIAF showed marked inter individual variation but were not associated with body mass index and were not influenced by prolonged semistarvation.

Based on sequence similarity to VEGF-A, a gene encoding a VEGF homologue has recently been discovered in the genome of Orf virus (OV) (Lyttle et al., 1994). Different isolates of Orf virus show significant amino acid sequence similarity to VEGF-A and described as a viral virulence factor that appears to be derived from captured host genes. All eight cysteine residues of the central cysteine knot motif characteristic of members of the VEGF family are conserved among other residues in the VEGF-E proteins (Dehio et al., 1999; Wise et al., 1999). Alignment of all mammalian VEGF sequences indicated that VEGF-E is distinct from the previously described VEGFs but most closely related to VEGF-A. Like VEGF-A, VEGF-E was found to bind with high affinity to VEGF receptor-2 (KDR) resulting in receptor autophosphorylation, whilst in contrast to VEGF-A, VEGF-E can not bind to VEGF receptor-1 (Flt-1). Furthermore VEGF-E can also not bind to VEGF receptor-3 (FLT-4). Therefore VEGF-E is a potent angiog

IRF1, IFN regulatory factor 1, is a member of the IFN regulatory transcription factor (IRF) family which regulates gene expression critical to immune response, hematopoiesis and proliferation. IRF-1 is a transcriptional activator for IFN-A, IFN-B, and IFN-G stimulated genes. IRF1 is also a tumor suppressor transcription factor inducing apoptosis of tumorigenic cell lines.

WIF1 binds to wnt proteins and inhibits their activities. WIF1 plays a role in mesoderm segmentation. WNT proteins are extracellular signaling molecules that take part in the control of embryonic development & cancer. WIF1 protein contains a WNT inhibitory factor (WIF) domain and 5 epidermal growth factor (EGF)-like domains. WIF1 takes part in mesoderm segmentation. WIF1 protein is found to be present in fish, amphibia and mammals. WIF1 is a recurrent target in human salivary gland oncogenesis. Downregulation of WIF1 takes part in the development and progression of pleomorphic adenomas. WIF1 is a tumor suppressor, specifically in nonfunctioning pituitary tumors.

IFN Regulatory Factor-5, also known as IRF5 belongs to the IFN regulatory factor (IRF) family, a group of transcription factors with various functions, including virus-mediated activation of IFN, and modulation of cell growth, differentiation, apoptosis, and immune system activity. Members of the IRF family are characterized by a conserved N-terminal DNA-binding domain containing tryptophan (W) repeats. Multiple transcript variants encoding different isoforms have been found for this gene. In addition, IRF5 is implicated in the induction of IFNs IFNA and INFB and inflammatory cytokines upon virus infection. IRF5 is activated by TLR7 or TLR8 signaling.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.