Overexpression of NF-κB–p65 protects L540Cy cells from arsenite-induced apoptosis.(A) L540Cy cells were transfected with a p65-GFP expression plasmid or with mock and pEGFP-N3 plasmids. Twenty-four hours after transfection, whole cell extracts were analyzed by Western blotting for the expression of p65-GFP and endogenous p65 using a p65-specific antibody. Western blot analysis of 2 independent experiments is shown. (B) Overexpression of NF-κB–p65 protects L540Cy cells from arsenite-induced apoptosis. L540Cy cells were transfected with a p65-GFP expression plasmid (p65-GFP; black bars) or with mock expression plasmid along with pEGFP-N3 (GFP; white bars). Twenty-four hours after transfection, p65-GFP expression was analyzed as described as for panel A and cells were incubated for 16 hours with the indicated concentrations of NaAsO₂. Thereafter, PI-stained cells were analyzed by FACS analysis. The decrease of viable GFP⁺, PI-cells is shown as percentage of viable transfected cells. The combined results of 4 independent experiments are shown; p65-GFP expression for 2 independent experiments is shown in panel A. Error bars denote SDs.