Figure 4. OSU-03012 and lapatinib treatment lowers ERK1/2 and AKT activity that correlates with lower MCL-1 expression. (A) GBM12 and GBM5 cells were treated with vehicle (DMSO); OSU-03012 (O, 1 μM); lapatinib (L, 1 μM) or the drugs combined. Cells were isolated 24h later and the phosphorylation of ERK1/2 and AKT (S473) determined, and the expression of MCL-1 determined. (B–D) GBM5, GBM12 and DAOY cells were infected with empty vector control (CMV) or with viruses to express active MEK1 (MEK1EE) or active AKT (caAKT). Twenty four h after infection cells were treated with vehicle (DMSO) or with lapatinib and OSU-03012. Cells were isolated after 48h and viability determined by trypan blue exclusion (n = 3, ± SEM). Arrows indicate the true percentage difference between vehicle and lap+OSU treatment.