This peptide is an inhibitor for tyrosine protein kinases such as EGFR and Src subfamily members (IC50 = 7.5 mM for pp60 v-src). The sequence corresponds to residues 140-160 of the proto-oncogene tyrosine protein kinase Src (c-Src).Val-Ala-Pro-Ser-Asp-Ser-Ile-Gln-Ala-Glu-Glu-Trp-Tyr-Phe-Gly-Lys-Ile-Thr-Arg-Arg-Glu or VAPSDSIQAEEWYFGKITRRE