Constitutive activation of Notch3 increases Tal1 expression. (A-B) Lymphoma cells derived from spleen of Notch3-IC Tg mice displayed high percentages of CD8 and CD8/CD4 cells; thus, Tal1 expression was analyzed by WB and RT-PCR in CD8⁺-selected thymocytes derived from either WT or Notch3-IC (N3Tg) mice (7-10 weeks). Each sample was analyzed in 2 serial dilutions as indicated (1:10, 1:100). β-Tubulin and β-actin, respectively, were used as loading control. (C) Immunoblot analysis of phosphorylated Tal1 (p-Tal1) or total Tal1 expression in whole-cell extracts of CD8⁺/DP WT, N3-IC Tg, and N3-IC Tg/pTα^-/- thymocytes (4-week-old mice). Tubulin was used as loading control.