Competitive repopulation of BM from wild-type and STAT5-deficient mice 48 hours following a single 5-FU injection.

Two separate experiments were performed using a male versus female competitive repopulation assay. In experiment no. 1, female donor mice were 5-FU treated, and in experiment no. 2, male donor mice were treated. In each case, the BM cells were mixed with the opposite sex cells harvested from PBS control–treated mice. BM cells were mixed at a 1:1 ratio, and the relative levels of male engraftment were determined by Southern blot analysis of pooled BM DNA obtained from 2 to 5 recipient mice. Two blots were probed with a male-specific probe, and a standard curve of male DNA mixed with female DNA was run on each gel (left panels). The y-axis for the standard curves is arbitrary units defined from the band volumes using ImageQuant software (Amersham Biosciences). On the right are the results of densitometry showing the percent contribution of the PBS-treated competitor.