Abelson-induced transformation is dependent on Stat5 in vivo. (A) Kaplan-Meier plot of Rag2^–/– mice that received a transplant of either Stat5a/b^+/+, Stat5a/b^null/+, or a 4:1 mixture of Stat5a/b^null/null and Stat5a/b^+/+ freshly Ab-MuLV–transformed bone marrow cells (5 mice/group; 1 × 10⁶ cells each mouse). Genotyping PCR analysis of mice used for 4:1 mixture is depicted. wt indicates wild type. (B) Immunoblotting for Stat5a/b of leukemic cells derived from bone marrow of Rag2^–/– mice that received a transplant of either Stat5a/b^+/+ or a 4:1 mixture of Stat5a/b^null/null/Stat5a/b^+/+ bone marrow. (C) PCR analysis of ex vivo–derived cell lines. Representative data of bone marrow (BM)–, peripheral blood (PB)–, spleen-, and lymph node (LN)–derived leukemic cell lines of one Rag2^–/– mouse that received a transplant of a 4:1 mixture of Stat5a/b^null/null/Stat5a/b^+/+ bone marrow cells, which was later killed. All cultures derived from Rag2^–/– mice that received transplants of Stat5a/b^null/null/Stat5a/b^+/+ cells were Stat5a/b^+/+ as determined by PCR analysis.