Fig. 4: Differential regulation of BAD protein phosphorylation and its biological effect.

a PPI interactions in the BAD complex. Red broken lines, PPIs enhanced in EGFRNet^mtKRAS-Hi vs. EGFRNet^mtKRAS-Lo; red solid lines, EGFRNet^mtKRAS-Hi exclusive interactions; gray, unchanged interactions. b Knocking down BAD expression significantly reduces apoptosis in mtKRAS^Hi but not mtKRAS^Lo cells. Apoptosis was measured 24 h post treatment. Ctrl., untargeted siRNA; BADkd, BAD specific siRNA. The reduction of BAD protein expression was assayed by Western blotting using tubulin (Tub) as loading control. Apoptosis assays represent three independent experiments; error bars are SD, and * means significant (P < 0.05) according to Student’s t-test; ns, not significant. c mtKRAS^Hi and mtKRAS^Lo cells were treated with the PRKA inhibitor H89 as indicated before BAD phosphorylation at S112 and S155 were assessed by Western blotting using phospho-specific antibodies. Numbers below lanes represent BAD phosphorylation normalized to total BAD protein expression. Samples shown in b and c are from the same Western blots, where irrelevant lanes were removed as indicated by vertical lines. d Apoptosis in response to 20 μM H89 treatment was assessed as in a. The data represent two independent experiments with 3 and 4 biological replicates, respectively. Error bars are SD, and * means significant (P < 0.05) according to Student’s t-test; ns, not significant. e A proposed model of the differential biological effect of PRKA due to differential PPIs. Source data are provided as a Source Data file.