Arg and Abl SH2 domains bind phosphorylated cortactin peptides Tyr(P)421 and Tyr(P)466, but not Tyr(P)482. Quantification of binding between Arg (A) and Abl (B) SH2 domains and peptides corresponding to phosphorylated (pY) and non-phosphorylated (Y) cortactin tyrosines 421, 466, and 482. Experiments were performed in triplicate and points represent mean ± S.E. (error bars may be obscured by data points). Data were fit using a one-site specific binding curve (GraphPad Prism) normalized to saturation (Bmax). C, table of binding affinities and mean ± S.E. from binding curves in A and B, peptides that showed no binding are labeled as N.B. D, sequences of cortactin peptides used in A and B.