Talin 1 R35E mutation does not impede αIIbβ3 integrin activation in CHO cells. (A) CHO-A5 cells stably expressing αIIbβ3 integrin were transfected with complementary DNA encoding EGFP-tagged THD in combination with Rap1b(Q63E) or Rap1GAP1. Integrin activation was assayed by binding of PAC1 to EGFP⁺ cells. Bar graph shows mean ± standard error of the mean (SEM) of 4 independent experiments. No significant differences between wild-type and mutants were detected. (B) Activation indices were normalized to the maximum value of THD(wild-type)–EGFP and plotted as a function of EGFP-MFI. Graphs represent mean ± SEM of 4 independent experiments. Curve fitting was performed using the total 1 site-binding model in Prism 5.0 (GraphPad Software). No significant difference between wild-type and mutants was detected. (C) Expression of EGFP-THD mutants was assayed by western blotting. *P < .05, **P < .01, ***P < .001, 2-way analysis of variance with Bonferroni posttest.