Fig. 3. Chronic PLK4 transgene activation does not affect hematopoietic recovery or transformation after IR.

rtTA and rtTA/Plk4 mice, 4 weeks of age, were exposed to a single dose of 1.75-Gy IR and kept on doxycycline for up to 7 days. (A) Bone marrow (BM) cellularity of two femora/animal was defined by cell counting in a hemocytometer. (B) Flow cytometry–based assessment of cellularity of the LSK cell fraction in (A). (C) Cellularity of the LK cell fraction in (A). (D) Cell numbers of spleen and (E) thymus were assessed at the indicated times in rtTA and rtTA/Plk4 transgenic mice kept on doxycycline-containing chow for up to 5 days after 1.75-Gy IR. (F) Kaplan-Meier analysis of tumor-free survival of rtTA and rtTA/Plk4 transgenic mice fed with doxycycline-containing chow after the last IR cycle (4 × 1.75 Gy). rtTA, median survival 176 days (n = 6); rtTA/Plk4, median survival 180 days (n = 7). Log-rank (Mantel-Cox) P = 0.9501 (χ² = 0.003911), Breslow-Gehan-Wilcoxon P = 0.8878 (χ² = 0.01990). Cell count data are shown as means ± SD and tested by Sidak’s multiple comparisons test. *P < 0.05, **P < 0.01, ***P < 0.005.