(A) Apoptosis and necrosis, quantified using an acridine orange assay, in SF767 cells after treatment with radiation, MP470, or both. MP470 (5 μ M) alone had no effect on the proportion of dead cells. Radiation (8 Gy) by itself induced some necrotic cell death but little apoptosis. However, the combination of MP470 followed by radiation greatly increased the proportions of both necrotic and apoptotic cells. Performed in triplicate: bars indicate mean ± SD. (B) Western blot analysis of SF767 cells treated with radiation (4 Gy) alone had no influence on the expression of glycogen synthase kinase (GSK)3β phosphorylated at serine 9; however, treatment with MP470 (10 μ M) or MP470 for 24 hrs followed by radiation enhanced the expression of this phosphorylated protein.