Specific residues involved in fibrinogen binding. The sequences of FGF-2 and FGF-1 in cassette C are shown. These are compared with the sequence of cassette C of 2 recombinant forms termed 221*2 and 221*1. The cassette C sequence in both of these mutants is derived from FGF-1 with the exception of the 5 residues indicated by bold letters and underlining that represent the corresponding, different residues derived from the FGF-2 sequence.