Cooperative growth-inhibitory effects of BCR/ABL inhibitors and HR antagonists on growth of CML cells. (A-D) K562 cells (A-B) and KU812 cells (C-D) were incubated with various concentrations of imatinib (STI571) (A,C) or AMN107 (B,D) in the absence (Control, ▪) or presence of cimetidine, 10 μM(•) or loratadine, 10 μM(▴)at 37°C for 48 hours. Thereafter, 3H-thymidine uptake was measured. Results are expressed as the percentage of control (Control) and represent the mean ± SD of triplicates. (E-F) K562 and KU812 cells were incubated in control medium (Control), imatinib (STI571), AMN107, loratadine, or terfenadine for 4 hours. Thereafter, cells were isolated and subjected to Western blot analysis using the antiphosphoprotein antibody 4G10 to detect the phosphorylated BCR/ABL oncoprotein (P-Bcr/Abl) (210 kDa) (top). β-actin served as loading control (bottom).
