pTα is insufficient to promote the survival of GSI-treated E2A^–/– lymphomas. (A) FACS analysis of E2A^–/– lymphoma (1.F9) infected with control (black histogram) or pTα (gray histogram) producing virus and stained with anti-hCD25 and anti–TCR-β antibody (solid lines) or control IgG (stippled lines). Anti–TCR-β staining is shown on hCD25⁺ cells. (B) Total cell numbers 48 hours after treatment of control (▪) or pTα (▦) virus–infected 16610D9, 1.F9, or 0531 lymphomas treated with DMSO (–) or GSI (+).