Y360 in CAP is the major phosphorylation site of c-Abl. A: Tyr residues 326, 360 and 632 in CAP were mutated into Phe and their phosphorylation upon c-Abl coexpression was analyzed as in Figure 2. No phosphorylation of CAP was detected in the absence of coexpressed Abl kinase. Y360F, Y632F, Y326F+Y360F and Y360+Y632F exhibited a reduced Tyr phosphorylation whereas Y326F was comparable to WT CAP. B: Quantitative analysis of the phosphorylation summarizing data from three experiments. The phosphorylation signals were normalized with the expression level of the respective variants and given as % of WT CAP phosphorylation. Error bars show standard deviation.