fig6

Figure 6. Effect of (A) 1-h and (B) 48-h treatments with different concentrations of pentoxifylline on P-gp activity of the NCI-H460/R cells, determined by the Rhodamine-123 accumulation assay. NCI-H460 cells were used as a negative control. The positive control consisted of NCI-H460/R cells treated with 20 μM verapamil. ^**P < 0.01; ^***P < 0.001; ^****P < 0.0001. P-gp: P-glycoprotein.