Fibroblast growth factor 1 (FGF1), also known as acidic fibroblast growth factor (aFGF) and heparin-binding growth factor 1 (HBGF-1), is a 17-18 kDa signaling protein. As a member of the FGF family, it possesses broad mitogenic and cell survival activities, playing critical roles in embryonic development, tissue repair, angiogenesis, and organogenesis. FGF1 exerts its pleiotropic effects by binding to and activating its tyrosine kinase receptors, FGFR1 through FGFR4, in a process that is potentiated by cell-surface heparan sulfate proteoglycans. This activation initiates several downstream signaling cascades, including the MAPK/ERK and AKT pathways. Originally purified in 1975 and distinguished from its homolog FGF2 by its acidic isoelectric point, FGF1 is unique in that it lacks a classical signal peptide and is secreted via a non-classical, stress-induced pathway involving S100A13 and SYT1. Beyond its well-established extracellular functions in wound healing and as a potent inducer of DNA synthesis, FGF1 also possesses intracellular activities and can translocate to the nucleus to influence cell survival.