Mutants of human fibroblast growth factor having increased stability and/or mitogenic potency

Mutants of human FGF-1 are disclosed having increased stability and mitogenic potency. In the FGF-1 polypeptide, primarily residue 12 is substituted with cysteine and/or residue 134 is substituted cysteine, valine or threonine to render the polypeptide more stable and/or to increase its mitogenecity.