MEHP and 15d-PGJ2 cooperatively induce apoptosis in cultured pro/pre-B cells and primary pro-B cells. (A) Suspension cultures of primary pro-B cells prepared from wildtype C57BL/6 mice were treated with Vh, MEHP (150 μM) and/or 15d-PGJ2 (2 μM) for 32 hr. (B) Suspension cultures of BU-11 cells were treated with ethanol:DMSO (50:50, Vh, 0.1%), MEHP (150 μM) or 15d-PGJ2 (10 μM) for the times indicated. (C-D) Suspension cultures of BU-11 cells pre-treated for 30 min with DMSO (Vh, 0.1%) or Z-VAD-FMK (30 μM) and then treated with ethanol:DMSO (50:50, Vh, 0.1%), MEHP (150 μM) or 15d-PGJ2 (10 μM) for 16 or 6 hr, respectively. Cell death was analyzed by hypotonic PI staining followed by flow cytometry. Data are presented as means ± SE from at least 3 independent experiments or 4 independently prepared and maintained pools of primary pro-B cells. *Statistically greater than Vh-treated (p<0.05, ANOVA, Dunnett’s). **Statistically different from all other treatment groups (p<0.05, ANOVA, Tukey-Kramer).