Effects of MAP kinase inhibitors and activators on the NaChl-induced apoptosis of K562 cells. (A) Cells were pretreated with the inhibitors for 30 minutes; then NaChl (10 μg/mL) was added and incubated for 24 hours. Apoptosis was determined by flow cytometric assay based on annexin V binding. (B) Cells were preincubated with the MAP kinase activators for 30 minutes before addition of NaChl, followed by determination of apoptosis at 24 hours by annexin V binding. Data represent mean ± SD of 3 experiments. *P < .01 versus NaChl treatment alone. SB indicates SB203580; PD, PD98059; Ani, anisomycin; and Con, control.