Fig. 2

Csk and Chk exhibit different efficiencies in phosphorylating and inhibiting Src. a Western blot of phosphorylated Tyr-416 (lower) and Tyr-527 (upper) of Src in the presence of Csk (0.014–0.7 μM) or Chk (0.013–1.04 μM). Relative Densitometry units (d.u) corresponding to the two tyrosine phosphorylation sites are presented. The experiment was repeated three times. In all three replicates, Csk and Chk induced the same pattern of changes in Src phosphorylation at both sites. b Enzymatic activity of Src after incubation with varying concentrations of Csk or Chk. The enzymatic activities of the “Src alone” reaction mixtures were used as the controls