Fig. 1.

Inhibition of NAMPT sensitizes primary human tissue to the growth inhibitory effects of MTX. Primary human fibroblasts were transfected with either control scrambled siRNA or with NAMPT-specific siRNA. (A) Twenty-four hours after transfection, cells were treated with MTX at concentrations up to 10 µM for 96 hours. (B) Isolated human lymphocytes were left unstimulated or were stimulated with 2% phytohemagglutinin and treated with either 10 nM MTX alone, 0.1 nM FK-866 alone, or 10 nM MTX in combination with 0.1 nM FK-866. Cell viability was measured by fluorescence spectroscopy using the resazurin reduction assay. Experiments were conducted in triplicate and the resulting mean ± S.D. for each experiment is presented. Statistical testing was conducted using t test analysis. Scr, scrambled.