Inhibition of colon tumor cell growth and DNA synthesis by SS and SSA. A and B, dose-dependent growth inhibitory activity of SS (A) and SSA (B) in human HT-29, HCT116, and SW480 colon tumor cells as measured by the CellTiterGlo assay described under “Materials and Methods.” C, the potency of SSA and SS, sulfone and sulfoxide to inhibit DNA synthesis in human HT-29 colon tumor cells. D, a time course experiment of SSA and SS to inhibit HT-29 tumor cell growth in which cell viability was measured using the CellTiterGlo assay. Columns, mean; bars, SE.