Figure 7.

PAK4 catalytic domain phosphorylates ICAP1 Ser-10 but not Ser-25 in vitro. A, alignment of the substrate recognition motif of the type II PAKs and the ICAP1 Ser-10 site. B and C, in vitro kinase assays were performed by incubating GST-ICAP1 or phosphomutants, PAK4 catalytic domain, and [γ-³³P]ATP for 30 min. B, representative autoradiograph and corresponding Coomassie-stained gel. C, phosphorylation of GST-ICAP1 mutants was quantified and normalized to WT GST-ICAP1 in four independent experiments. Individual values are represented by filled circles, and bars show mean with S.D. ****, p ≤ 0.0001 with respect to WT GST-ICAP1 as determined by a one-way ANOVA test with Fisher's LSD test with multiple comparisons.