DMS inhibits the growth and increases apoptosis of HS1 and HS2 cells cultured in low serum level. (A) 663 HS1 cells and 921 HS2 cells were cultured for the indicated times in a medium containing 10% serum in the presence or absence of 10 μM DMS and in the presence of Epo (1 U/mL) for 663 HS1 cells. The means and standard deviations were determined from 5 experiments. ○ indicates 663; •, 663 + DMS; ▵, 921; and ▴, 921 + DMS. (B) Percentages of dead cells were determined by trypan blue exclusion assay on 663 and 921 cells cultured in a medium containing 1% serum in the presence or absence of 10 μM DMS for 24 hours or 48 hours. Data are means ± SD of 5 experiments performed in duplicate. ^* indicates statistical significance by Student t test: P < .01 compared with the control. ▦ indicates 663; □, 663 + DMS; ▪, 921; and ▨, 921 + DMS. (C) The pEF-BOS empty vector and expression construct for MT-SPHK1^G81D were transfected into 921 cells. Expression of MT-SPHK1^G81D in whole-cell lysates from cell clones transfected with pEF-BOS and pMSCV-Neo (921-B) and with pEF-BOS-MT-SPHK1^G81D and pMSCV-Neo (921-G3 and 921-G5) was analyzed by Western blotting using anti-SPHK1 antibodies. Reprobing the same membrane with anti-α adaptin was used as loading control. (D) Proliferation of pEF-BOS-transfected cells (921-B1) and MT-SPHK1^G81D-transfected cells (921-G3 and 921-G5) in a culture medium containing 1% serum. The graphs depict means ± SD of 4 independent experiments performed in duplicate. □ indicates 921-B; ▵, 921-G3; and •, 921-G5. (E) Percentages of dead cells were determined by trypan blue exclusion assay on 921-B1, 921-G3, and 921-G5 cells cultured for 24 hours and 48 hours in a medium containing 1% serum. Data are means (±SD) of 4 experiments in duplicate. ^* indicates statistical significance by Student t test: P < .05 compared with the control. ▪ indicates 921-B1; ▦, 921-G3; and ▨, 921-G5.