Evolutionary relationships within the FGF family. (a) Apparent evolutionary relationships between FGFs from vertebrates, invertebrates and a virus. Amino-acid sequences of nine representative FGFs were chosen from human and compared with FGFs from Drosophila, C. elegans, zebrafish and Autographa californica nuclear polyhedrosis virus. (b) Apparent evolutionary relationships of the 22 known human and murine FGFs. Sequences were aligned using Genetyxsequence analysis software and trees were constructed from the alignments using the neighbor-joining method.