Fibroblast Growth Factors, FGFs, are a 22 member family of Proteins known to be involved in angiogenesis, wound healing and embryonic development. As a family, they bind to heparin and signal through four receptor tyrosine kinases called, FGFR1, 2, 3 and 4. Although the mechanism remains unclear, FGF-basic, or FGF-1, is a critical component in keeping embryonic stem cells undifferentiated in cell culture systems. Recombinant FGF basic is a non-glycosylated Protein, containing 145 amino acids, with a molecular weight of 16.3 kDa.