Effect of low-dose GM-CSF on procaspase protein levels, mRNA expression, and caspase 3 activation and PARP cleavage. (A) Growth factor–deprived OCIM2 cells were incubated in the absence of GM-CSF and in the presence of 0.025 μg/mL GM-CSF for 20 minutes, 40 minutes, and 1, 2, 3, 4, 6, and 8 hours. Procaspase protein levels were scored by densitometry and their numerical values were divided by the densitometry values obtained from the corresponding loading controls. The signals obtained at different time points following incubation with GM-CSF are depicted. A band of β-actin (upper band) is presented as loading control. (B) The changes in mRNA levels were recorded prior to and after incubation with 0.025 μg/mL GM-CSF for 20 minutes, 40 minutes, and 1 and 2 hours. RNA obtained from Hela cells was used as a positive control, and L32 was the loading control. The figure depicts mRNA of procaspases 8, 3, 10, 7, 1, 2, and 9. (C) Growth factor–deprived OCIM2 cells were incubated with 0.025 μg/mL GM-CSF as in previous experiments. Procaspase 3, caspase 3, and PARP protein levels were detected at different time points by Western immunoblotting. Representative data from 3 different experiments are shown.