Location and structure of site-directed mutants. (A) Amino acid sequence of cassettes C and D of FGF-2 and FGF-1. Bold characters represent identical residues between FGF-1 and FGF-2. The 4 regions that were selected for site-directed mutagenesis are indicated by lines above the sequence. (B) Structures of recombinant FGF forms made by site-directed mutagenesis. The ovals indicate the cassettes in which changes in sequence were made. FGF-2_1D, _2D, _3D represent deletion mutants in which the residues in parentheses were removed. FGF-2_1S, _2S, _3S represent substitution mutants in which the residues in bold derived from FGF-1 were substituted into the FGF-2 cassette. Residues in bold with underlining are derived from FGF-1.