FGF1 also designated Heparin-binding growth factor 1 precursor (HBGF-1) ; Acidic fibroblast growth factor (aFGF). heparin-binding growth factors are angiogenic agents in vivo and are potent mitogens for a variety of cell types in vitro. There are differences in the tissue distribution and concentration of these 2 growth factors. Subunit si monomer.FGF1 belongs to the heparin-binding growth factors family. may play a role in neurite outgrowth; may regulate cell differentiation in the nervous system; may act in synergy with fibronectin to enhance neuronal cell adhesion.