MITF and FoxO3a regulate apoptosis following inhibition of PI 3-kinase. A, proliferating T98G cells were transfected with nonspecific, USF1, MITF, or FoxO3a siRNA for 48 h. Transfected cells were treated with LY294002 for 40 h. Cell viability was determined by MTT assay both prior to and after treatment with LY294002, and results are presented as the percentage of cell death following LY294002 treatment. Data are the mean ± S.E. of 6 independent samples. Knockdown of both MITF and FoxO3a significantly reduced cell death (p < 0.001). B, proliferating T98G cells were transfected with nonspecific, ATROGIN-1, CCNG2, and TXNIP siRNA for 48 h. Transfected cells were treated with LY294002 for 40 h. Cell viability was determined by MTT assay both prior to and after treatment with LY294002, and results are presented as the percentage of cell death following LY294002 treatment. Data are the mean ± S.E. of 10 independent samples. Knockdown of ATROGIN-1 and TXNIP significantly reduced cell death (p < 0.005).