Expression of Notch1 target genes in E2A^–/– and p53^–/– lymphomas. (A) Northern blot of total RNA isolated from the indicated lymphomas probed with Notch1 or actin cDNA. (B) Western blot of protein isolated from the indicated lymphomas 24 hours after treatment with GSI (+) or DMSO (–) using anti–activated Notch1 (V1744) antibody. The position of molecular mass markers, in kilodaltons, is shown to the left of the blot. (C) Northern blot of total RNA isolated from the indicated lymphomas probed with Deltex1, Hes1, Notch3, nRARP, pTα, and actin cDNA. 0531 and 1.F9 are E2A^–/–, and 16610D9, K052FA2, K052FA2C1, and K052DA20 are p53^–/– lymphoma lines. E2A^–/– and p53^–/– lymphomas are primary tumors isolated directly from mice.