Inhibition of p38 activity inhibits proliferation but not induction of apoptosis in HCD57(K) cells.
(A) Proliferative response of HCD57 cells to EPO and SB203580. HCD57(K) cells were washed and treated with no additional growth factor (columns 1-3) or EPO (columns 4-9) in the presence of DMSO vehicle (V, columns 2, 5, and 8), or 20 μmol/L SB203580 (SB) (columns 3,6, and 9) for 24 hours (columns 1-6) or 72 hours (columns 7-9). Data are indicated as the number of cells as a percentage of the starting number of cells. In this experiment, nonviable cells were 5% or less. (B) Cells incubated 24 hours in the presence or absence of EPO or inhibitor as indicated were stained with propidium iodide as indicated in “Materials and methods” and analyzed by using flow cytometry. The number of apoptotic cells is indicated as a percentage of the total number of cells containing sub-G0/G1 DNA and is indicated as M1 on plots.
