Mouse FGF1, which is produced by multiple cell types, stimulates the proliferation of all cells of mesodermal origin and many cells of neuroectodermal, ectodermal, and endodermal origin. It plays a number of roles in development, regeneration, and angiogenesis. It is released extracellularly as a disulfide-linked homodimer and is stored in complex with extracellular heparan sulfate. Intracellular Mouse FGF1 functions as a survival factor by inhibiting p53 activity and proapoptotic signalin.