Figure 4.

Maintenance of LSK quiescence abrogates LSK apoptosis in Rad50^S/S mice. A, the percentage of Lin⁻ Sca-1⁺ c-kit⁺ (LSK) cells from 2-week-old WT, Mef^−/−, p21^−/−, Rad50^S/S, Rad50^S/SMef^−/−, and Rad50^S/S p21^−/− mice is plotted (n = 6). P = 0.02, Rad50^S/S versus Rad50^S/S p21^−/−; P = 0.01, Rad50^S/S versus Rad50^S/S Mef^−/−. B, percentage of Ki-67 and Hoechst double-negative LSK cells from the mice depicted in A. Symbols as in A. P = 0.631, Rad50^S/S versus Rad50^S/S p21^−/−; P = 0.037, Rad50^S/S and Rad50^S/S Mef^−/−. C, percentage of Annexin V–positive LSK cells from the mice depicted in A. Symbols as in A. P = 0.423, Rad50^S/S versus Rad50^S/S p21^−/−; P = 0.004, Rad50^S/S versus Rad50^S/S Mef^−/−. D, WT, Mef^−/−, Rad50^S/S, and Rad50^S/S Mef^−/− LSK were pushed into cycle with 2-d sequential injections of 250 μg/kg G-CSF. On day 3, the percentage of LSK cells in bone marrow was measured (n = 4; left). Middle and right, the percentages of Annexin V–positive or Ki-67 and Hoechst double-negative LSK cells are plotted, respectively.