Figure 4.

Enhanced depletion of intracellular NAD(P)H levels in cells with reduced XRCC1 expression (A) NAD(P)H depletion was measured after 4 h of MMS treatment either in the presence or in the absence of the PARP-1 inhibitor 3-AB (10 mM). The decrease was calculated by dividing the measured values of MMS-treated cells by the values of mock-treated cells. Measurements were done in triplicate. Shown are the values of one typical experiment. (B) Expression levels of PARP-1 in cells used for the depletion experiments were verified by western blotting of proteins extracted from MDA-MB-549 cells, which were either mock-treated or exposed to 200 μg/ml MMS for 1 h, followed by an incubation in drug-free medium for 3 h.