FGF acidic, also known as ECGF, FGF-1and HBGF-1, is a non-glycosylated heparin binding growth factor that is expressed in the brain, kidney, retina, smooth muscle cells, bone matrix, osteoblasts, astrocytes and endothelial cells. It is a mitogenic peptide that is produced by multiple cell types and stimulates the proliferation of cells of mesodermal, ectodermal, and endodermal origin. Its association with heparan sulfate is a prerequisite for activation of FGF receptors. Internalized FGF acidic migrates to the nucleus where it is phosphorylated by nuclear PKC delta, exported to the cytosol, dephosphorylated, and degraded. Intracellular FGF acidic inhibits p53 activity and proapoptotic signaling.