Lef1 expression is dependent on Notch signaling. (A) Northern blot of RNA isolated from the p53^−/− lymphoma line 16610D9 (which does not have active Notch signaling), N3T, and E2A^−/− lymphoma lines 0531, 1.F9, and 0714 (which have active Notch signaling) 24 hours after treatment with DMSO or GSI or 48 hours after infection with MigR1-DN-MAML (DN). (B) Western blot of 16610D9, 0531, or 1.F9 cells 20 or 40 hours after treatment with DMSO (−) or GSI (+) using Lef1-specific antibody. Relative expression of Lef1 (C) or Deltex1 (D) in the E2A^−/− lymphoma 1.F9, the E2A^−/−Rag2^−/− lymphoma 531026, and the p53^−/− lymphoma K052FA2C1 (FA2C1) cultured in DMSO or GSI for 24 hours. Expression was determined by QPCR and standardized to HPRT. Error bars represent the standard error of triplicate measurements.