Nilotinib inhibited P-gp activity in human STS cells.

<p>Intracellular Rho-123 fluorescence (0.5 or 0.05 µM) was estimated by flow cytometry in synovial sarcoma SW982 cells after 2 h treatment or in leiomyosarcoma SK-UT-1 cells after 24 h treatment with vehicle (DMSO), imatinib (1–10 µM), nilotinib (1–10 µM) or verapamil (10 µM). <i>Left</i>, Median of intracellular Rho-123 fluorescence in the absence (vehicle, V) or presence of TK inhibitors normalized to vehicle-treated cells (taken as 100%). Each column represents mean ± SEM of five independent experiments. <i>Right</i>, Representative flow cytometry analysis of the intracellular Rho-123 fluorescence in the absence (vehicle) or presence of imatinib (10 µM) or nilotinib (10 µM) detected with excitation at 488 nm and emission at 580 nm. T0 was the intracellular Rho-123 fluorescence measured at t = 0. ^*<i>P</i><0.05 and ^***<i>P</i><0.001 versus vehicle-treated cells.