Expression of quiescence-associated genes in Ku70^−/−HSCs. BM was isolated from 3 independent groups of WT, Ku70^−/−, and TgBcl2, TgBcl2/Ku70^−/− mice, and LSK cells were sorted before messenger RNA isolation. The relative messenger RNA expression levels of c-Mpl, p57, p27, p53, p21, Hoxa5, Hoxa9, Hoxb4, and CXCR4 were evaluated by quantitative real-time reverse-transcription PCR with endogenous control GAPDH in triplicate. Means from 3 or 4 independent experiments are shown. Error bars indicate SD, and significance was determined by a 2-tailed Student t test. *P < .05.