NaChl treatment enhances phosphorylation of p38 and ERK1/2 MAP kinases in K562 cells. (A) Cells were treated with NaChl (10 μg/mL) for indicated time periods, fixed, permeabilized, and stained with isotype-matched control mouse monoclonal antibodies (filled histogram) or anti–phospho-p38 and anti–phospho-ERK1/2 monoclonal antibodies (solid line). Values within histograms represent the specific MFI (after subtracting the control values). (B) NaChl treatment does not alter MAP kinase protein expression in K562 cells. Expression of ERK (□) and p38 (○) is presented as mean fluorescence intensity (MFI). Data presented are mean ± SD of 3 experiments. (C) Immunoblot-based determination of p38 and ERK phosphorylation in K562 cells before and after NaChl treatment. Cells were left untreated or treated with NaChl (10 μg/mL) for 30 minutes and 3 hours before analysis. (D) NaChl treatment enhances p38 phosphorylation only in Bcr-Abl–positive cells. A panel of Bcr-Abl–positive CML cell lines (KCL22, KU812), Bcr-Abl–negative lymphoid (Molt 4, REH), myeloid (U937, THP-1), squamous cell carcinoma (HSC-2), and salivary gland tumor cell line (HSG) were left untreated or treated with NaChl (500 μg/mL for HSG and HSC-2 cells and 10 μg/mL for other cells) for 30 minutes and 3 hours before analysis by immunoblots with indicated antibodies.