Fig 3. Inhibition of ABCB1 significantly reduces resistance in ABCB1 overexpressing K562 cells.

p-CRKL dependent IC50 (dose of TKI required to reduce p-CRKL levels by 50%) was calculated by western blot in at least four independent experiments with the average IC50 values from the resultant densitometry analyses denoted by the columns. Statistical analyses compared resistant cells in the presence vs. absence of ABCB1 inhibition (asterisks) and also resistant cells in the absence and presence of ABCB1 inhibitors with control cells in the absence of inhibitor (carets). Analyses were performed using unpaired Student’s t-test (Welch’s correction was applied for data groups with unequal SD) or Mann-Whitney Rank Sum test. Statistically significant p-values are denoted by carets (^) or asterisks (* p<0.05; ** p<0.01; *** p<0.001). Error bars represent SEM. NIL = nilotinib; cyclo = cyclosporine; PSC = PSC-833.