Figure 2.

DMS increases expression of SphK1 in U937 cells. U937 cells were treated with vehicle or with 15 μM DMS for 24 h (A) or with the indicated concentrations of DMS for 4 or 6 h (B, C). A) Cells were lysed and equal amounts of protein (60 μg) were separated by SDS-PAGE and immunoblotted with anti-SphK1 antibody. Blots were stripped and reprobed with anti-tubulin antibody as loading controls. Lysates from M2 melanoma cells transfected with scrambled siRNA or siRNA targeted to SphK1 were included as controls to indicate the molecular weight of SphK1. B, C) Cells were stained with annexin V/PI. Apoptotic cells are annexin V-positive (B), whereas necrotic cells are PI-positive only (C). Similar results were obtained in four independent experiments. *P < 0.05.