Pten overexpression delays B-ALL development. (A) Overexpression of Pten alone or in combination with imatinib treatment prolonged survival of B-ALL mice. Mice with B-ALL induced with BCR-ABL-GFP (n = 10) or BCR-ABL-PTEN-GFP (n = 10) were treated with a placebo (n = 5) or imatinib (n = 5, 100 mg/kg, twice a day by gavage), beginning at day 8 after BMT. (B) FACS analysis showed a slower accumulation of GFP⁺B220⁺ leukemia cells in peripheral blood of recipients of BCR-ABL-PTEN-GFP transduced bone marrow cells than that in recipients of BCR-ABL-GFP–transduced bone marrow cells. (C) The difference in peripheral blood leukemia cell counts (white blood cell count × percentage of GFP⁺B220 cells) in B-ALL mice induced with BCR-ABL-GFP or BCR-ABL-PTEN-GFP was determined at day 12 or 20 after BMT. (D) Mice with B-ALL induced with BCR-ABL-PTEN-GFP were treated with a placebo or imatinib (IM). Peripheral blood leukemia cells were analyzed by FACS at day 35 after BMT. (E) Western blot analysis of spleen cell lysates for Pten overexpression and Akt phosphorylation in mice with B-ALL induced by BCR-ABL-PTEN-GFP or by BCR-ABL-GFP mice. The protein lysates were isolated from the mice at day 20 after BMT. The black line indicates that the lanes not adjacent on the same original sodium dodecyl sulfate–polyacrylamide gel electrophoresis were brought together to generate this figure.