Impact of mutations of PDEδ residues on KRAS4b–PDEδ interaction. (A) Position of eight PDEδ residues that were mutated in this study. ITC measurements showing dissociation constant of KRAS4b-FMe with PDEδ mutants (B) PDEδ-F15A, (C) PDEδ-M20A, (D) PDEδ-W32A, (E) PDEδ-W90A, (F) PDEδ-Q116A, (G) PDEδ-I129A, and (H) PDEδ-F133A. DP, differential power.