ON 013100 inhibits the proliferation of MCL (JEKO-1 and MINO), breast (MCF7 and MDA-MB-231), gastric (AGS), and esophageal (OE19, OE33, and FLO-1) cancer cell lines at a nanomolar concentration (ON 013100 GI50=6.7-11.2 nM). ON013100 significantly alters the cell cycle profile, dramatically increasing the number of cells in the G2/M phase. Treatment of the cells with even 0.1 μM of ON013100 results in an arrest of the G2/M phase of the cell cycle. ON-013100 induces apoptosis and has activity against most human cancer cell lines in vitro[2][3].