Figure 8.

IQ domain-containing GTPase-activating protein 1 (IQGAP1) promotes sustained S6 activation and global protein synthesis in natural killer (NK) cells. (A) Phosphorylation of S6 at Ser^235/236 and Ser^240/244 was evaluated by western blot in IL-2 cultured wild-type (WT) and Iqgap1^−/− NK cells at the indicated times post-NKG2D stimulation. Total S6 was used to calculate representative fold changes which are shown relative to unstimulated WT NK cells and quantification of four independent western blots is shown in (B) for both S6 phosphorylation sites. Global protein synthesis in WT and Iqgap1^−/− NK cells was assessed by puromycin incorporation as described in the Materials and Methods section. (C) Representative histograms of puromycin incorporation gated from CD3ε⁻NK1.1⁺ NK cells are labeled with MFIs and (D) fold change in MFI was calculated relative to WT NK cells not treated with puromycin. Cycloheximide (CHX) was added during the experiment as a negative control for global protein synthesis. Error bars represent SD using four to six mice in at least two independent experiments, **p < 0.01 using two-way ANOVA accounting for multiple comparisons.