Sin3B^CKOanimals are sensitized to myelosuppressive therapy. (A) Survival analysis of control and Sin3B^CKO animals injected weekly with 150 mg/kg 5-FU. Arrows indicate days of injection (days 0, 7, and 14); n = 9 per genotype. (B) Absolute leukocyte count in the peripheral blood after serial injections of 5-FU. Arrows indicate days of injection (days 0 and 7). Days 0 and 7 counts are prior to 5-FU injection; n ≥ 3. (C) Absolute leukocyte count in the peripheral blood after a single injection of 5-FU. Arrow indicates day of injection (day 0). Day 0 counts are prior to 5-FU injection; n ≥ 3. Frequency (D) and cell number (E) of indicated populations in the bone marrow at day 12 following 5-FU injection; n ≥ 3. (F) Quantification of the distribution of HSCs in the G0, G1, and S/G2/M phases of the cell cycle at day 12 following 5-FU injection; n ≥ 3. Data are represented as mean ± SEM. *P < .05; **P < .01.