Pharmacologic inhibition of MEK/ERK kinase reverses the KRAS^G13D-induced deregulation of the alt-NHEJ. (A) Protein expression of p-ERK1/2^{Thr202/Tyr204}, ERK1/2, XRCC1, PARP1, Lig3α, and actin in cell extracts of transduced CCRF-HSB2 cells treated with the selective MEK inhibitor PD98059 (200 µM) for 24 hours. Shown is 1 representative analysis of 2 independent experiments. Bar graph shows protein expression levels relative to actin determined by the means of densitometry of 2 independent experiments. (B) CCRF-HSB2 cells transduced with either EV or pLenti6.2-KRAS^G13D were treated with the selective MEK inhibitor PD98059 (200 µM) for 24 hours. After incubation, cells were transfected with either HindIII- or I-SceI–digested linearized plasmid in combination with pDsRed2-N1 as a transfection control. After an incubation period of 24 hours, end-joining efficacy was determined by flow cytometry. Data represent mean values ± SD of 3 independent experiments (*P < .05, Student t test). (C) Protein expression of p-Akt^Thr308, p-Akt^Ser473, Akt, XRCC1, PARP1, Lig3α, and actin in cell extracts of transduced CCRF-HSB2 cells treated with the Akt inhibitor SH-6 (10 µM) for 24 hours. Shown is 1 representative analysis of 2 independent experiments. (D) CCRF-HSB2 cells transduced with either EV or pLenti6.2-KRAS^G13D were treated with the Akt inhibitor SH-6 (10 µM) for 24 hours. After incubation, cells were transfected with either HindIII- or I-SceI–digested linearized plasmid in combination with pDsRed2-N1 as a transfection control. After an incubation period of 24 hours, end-joining efficacy was determined by flow cytometry. Data represent mean values ± SD of 2 independent experiments.