Fig. 7.

NAMPT inhibition results in the synergistic depletion of cellular ATP by MTX. (A and B) A549 cells transfected with either control scrambled siRNA or with siRNA directed toward NAMPT were treated with different concentrations of MTX and cellular ATP levels were measured 96 hours after transfection (A) and in response to treatment with different concentrations of MTX over 96 hours (B). The effect of MTX on cellular ATP was determined by normalizing cellular ATP levels to the untreated control cells. Experiments were conducted in triplicate and the resulting mean ± S.D. for each experiment is presented and compared by t test analysis. Scr, scrambled.