dATP-dependent activation of CPP32 in vitro. An aliquot (10 μL) of cytosol was incubated with 0, 0.1, or 1 mmol/L dATP at 37°C for 60 minutes. HL-60 cells (lanes 1 through 3), K562 cells (lanes 4 through 6), BALM3 cells (lanes 7 through 9), U937 cells (lanes 10 through 12), THP-1 cells (lanes 13 through 15), HEL/S cells (lanes 16 through 18), ML-1 cells (lanes 19 through 21), and NB4 cells (lanes 22 through 24). P32; CPP32, and P20; 20-kD fragment of CPP32 (active form).