Immediate-early protein playing a role in various cellular processes including proliferation, adhesion, migration, differentiation and survival (PubMed:12050162, PubMed:12695522, PubMed:15181016, PubMed:15611078, PubMed:21344378). Acts by binding to integrins or membrane receptors such as NOTCH1 (PubMed:12695522, PubMed:15611078, PubMed:21344378). Essential regulator of hematopoietic stem and progenitor cell function (PubMed:17463287). Inhibits myogenic differentiation through the activation of Notch-signaling pathway (PubMed:12050162). Inhibits vascular smooth muscle cells proliferation by increasing expression of cell-cycle regulators such as CDKN2B or CDKN1A independently of TGFB1 signaling (PubMed:20139355). Ligand of integrins ITGAV:ITGB3 and ITGA5:ITGB1, acts directly upon endothelial cells to stimulate pro-angiogenic activities and induces angiogenesis. In endothelial cells, supports cell adhesion, induces directed cell migration (chemotaxis) and promotes cell survival (PubMed:12695522). Also plays a role in cutaneous wound healing acting as integrin receptor ligand. Supports skin fibroblast adhesion through ITGA5:ITGB1 and ITGA6:ITGB1 and induces fibroblast chemotaxis through ITGAV:ITGB5. Seems to enhance bFGF-induced DNA synthesis in fibroblasts (PubMed:15611078). Involved in bone regeneration as a negative regulator (By similarity). Enhances the articular chondrocytic phenotype, whereas it repressed the one representing endochondral ossification (PubMed:21871891). Impairs pancreatic beta-cell function, inhibits beta-cell proliferation and insulin secretion (By similarity). Plays a role as negative regulator of endothelial pro-inflammatory activation reducing monocyte adhesion, its anti-inflammatory effects occur secondary to the inhibition of NF-kappaB signaling pathway (PubMed:21063504). Contributes to the control and coordination of inflammatory processes in atherosclerosis (By similarity). Attenuates inflammatory pain through regulation of IL1B- and TNF-induced MMP9, MMP2 and CCL2 expression. Inhibits MMP9 expression through ITGB1 engagement (PubMed:21871891). Brain osteoanabolic hormone (By similarity). Drives osteogenesis in osteochondral skeletal stem cells (PubMed:38987585). During lactation, maintains the maternal skeleton and viability of offspring (By similarity). {ECO:0000250|UniProtKB:Q64299, ECO:0000269|PubMed:12050162, ECO:0000269|PubMed:12695522, ECO:0000269|PubMed:15181016, ECO:0000269|PubMed:15611078, ECO:0000269|PubMed:17463287, ECO:0000269|PubMed:20139355, ECO:0000269|PubMed:21063504, ECO:0000269|PubMed:21344378, ECO:0000269|PubMed:21871891, ECO:0000269|PubMed:38987585}. This is the function of ENSG00000136999 (CCN3, cellular communication network factor 3).