Immediate-early protein playing a role in various cellular processes including proliferation, adhesion, migration, differentiation and survival. Acts by binding to integrins or membrane receptors such as NOTCH1. Essential regulator of hematopoietic stem and progenitor cell function. Inhibits myogenic differentiation through the activation of Notch-signaling pathway. Inhibits vascular smooth muscle cells proliferation by increasing expression of cell-cycle regulators such as CDKN2B or CDKN1A independently of TGFB1 signaling. 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. 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 (By similarity). 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 (By similarity). 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:22353423). Interacts with FBLN1. Interacts (via CTCK domain) with NOTCH1 (via the EGF-like repeat region) (By similarity). Interacts with GJA1/CX43 (PubMed:15181016, PubMed:15213231). Interacts with ITGA5:ITGB1, ITGAV:ITGB3 and ITGAV:ITGB5 (By similarity). Interacts with ZDHHC22; the interaction may lead to CCN3 palmitoylation (By similarity). Localizes at the gap junction in presence of GJA1. Widely expressed. Highly expressed in neurons of dorsal root ganglia and dorsal horn of the spinal cord (at protein level) (PubMed:22353423). Expressed in astrocytes (at protein level) (PubMed:15213231). In cartilage, dominantly expressed in the chondrocyte territorial matrix (PubMed:21871891). During persistent inflammatory pain the expression levels are down-regulated. May be palmitoylated on Cys-238, which is important for extracellular secretion. Belongs to the CCN family.