Decreased expression of bcl-x_L and increased erythroblast apoptosis correlate with anemia in Stat5a^−/−5b^−/− neonates.

(A) Flow cytometry histograms for bcl-x_L expression in neonatal spleens. The left-hand histogram contains data from all spleen cells of one representative wild-type neonate and one Stat5a^−/−5b^−/− neonate. The right-hand histogram contains data from CD71^high (early erythroblasts) cells only for the same spleens. In wild-type spleens, 65% of all cells and 94% of CD71^high cells express bcl-x_L(within the marker “M1”). In Stat5a^−/−5b^−/−spleens, 11% of all cells and 9% of CD71^high cells express bcl-x_L. (B) Summary of bcl-x_L and annexin V binding data on representative neonates from 2 litters analyzed in the same experiment. Bcl-x_L was measured as in panel A; annexin V was measured as described in Figure 8. Correlation lines were fitted to all the data points.