Inhibition of Notch1 affects the expression of Notch1 target genes in E2A^–/– lymphomas. (A) Northern blot of total RNA isolated from lymphomas treated with DMSO or GSI for 48 hours or sorted GFP⁺ cells from DN-MAML–expressing cells harvested 48 hours after infection. The blot was probed sequentially with the indicated cDNA probes. (B) Flow cytometric analysis of cell surface TCR-β on E2A^–/– lymphomas treated with DMSO (black histogram) or GSI (gray histogram) for 24 hours. Broken line represents staining with irrelevant fluorescently labeled antibody.