HLFs were transfected with (A) mock, (B) akt1, (C) erk1, (D) erk2, or (E) erk1/2 + akt1 siRNA via nucleofection. HLFs at 48 hr post-transfection were incubated with 0, 1, and 2 μM Na2CrO4 for 24 hr in the absence or presence of 10 μM SOV, then seeded for colony formation. Data are expressed as percent clonogenic survival of Cr 0 μM control, and are the average ± SE from 2–5 independent experiments performed in triplicate. *: statistically significant difference between the samples with and without SOV at p<0.05. (F)p-Erk1/2 protein expression level after transfection with either mock or erk1/2 siRNA in the presence of DMSO or U0126. HLFs at 48 hr post-transfection with indicated siRNA were treated with 100 μM U0126 or its vehicle control DMSO for 24 hr, then protein lysates were extracted and analyzed for p-Erk1/2 and α-tubulin (loading control) by immunoblotting. Numbers under the p-Erk1/2 blot show p-Erk1/2 expression normalized by α-tubulin level.