Ubiquitination-resistant Bfl-1ΔC induces massive splenomegaly when coexpressed with p53DD in nude mice. (A left) Western blot of FL5.12 cells stably expressing p53DD or GFP-Bfl-1 alone or coexpressing p53DD with either GFP-Bfl-1, GFP-Bfl-1ΔC or GFP-Bcl-xL. (Right) Reverse transcriptase polymerase chain reaction shows equivalent amounts of GFP-Bfl-1 and GFP-Bfl-1ΔC mRNA in FL5.12 cell lines stably expressing GFP-Bfl-1/p53DD, GFP-Bfl-1ΔC/p53DD, or GFP-Bfl-1 alone. (B) Kaplan-Meier curves showing overt manifestation of disease in athymic nude mice (Balb/c nu⁺/nu⁺) injected intravenously with FL5.12 cells expressing p53DD alone (green), GFP-Bfl-1 alone (purple), GFP-Bfl-1/p53DD (orange), GFP-Bfl-1ΔC/p53DD (red), or GFP-Bcl-xL/p53DD-positive control (black). The arrowhead denotes a mouse that died of unknown cause. P values were determined by Student t test (GFP-Bfl-1ΔC/p53DD vs p53DD or GFP-Bfl-1 or GFP-Bfl-1/p53DD, P = .001; GFP-Bfl-1ΔC/p53DD vs GFP-Bcl-xL/p53DD, P = .042). (C) Splenomegaly in a representative GFP-Bfl-1ΔC/p53DD mouse compared with p53DD alone. Scale bar, 1cm. (D) Plot of average spleen weight at euthanasia.