In vivo evidence for decreased leukemogenicity in Skp2^−/− mice. (A) Flow cytometric analysis of 5-FU–treated Skp2^+/+ and Skp2^−/− mice bone marrow cells for stem/multipotent progenitor population (left) and lineage surface markers (right). Significant differences (P < .05) are indicated by an asterisk. Error bars represent SE. (B) Kaplan-Meier survival curve for mice transplanted with Skp2^+/+ and Skp2^−/− marrow transduced with p210^BCR-ABL. The number of individual mice in each arm is indicated. Mice transplanted with Skp2^−/− marrow survived significantly longer (P = .003). (C) Southern blot analysis for proviral integration from BCR-ABL or empty vector transduced Skp2^+/+ and Skp2^−/− mice. Genomic DNA from spleen tissue (15 μg) was digested with restriction enzyme BglII, resolved on a 1.5% agarose gel, and transferred to Hybond-N⁺ membrane. The blots were hybridized with a ³²P-labeled GFP probe and exposed to autoradiography film.