Cdk6 deletion ameliorates symptoms associated with JAK2^V617Fmutation. (A) Time course of blood counts of transgenic mice (n = 6 per genotype). Results are presented as means + standard deviation (SD). Two-way analysis of variance (ANOVA) with subsequent Bonferroni posttest was used, and significance between VavCre; JAK2^V617F; Cdk6^+/+ and VavCre; JAK2^V617F; Cdk6^−/− is indicated. *P < .05; **P < .01;***P < .001; ****P < .0001. HCT, hematocrit; HGB, hemoglobin; n.s., not significant; RBC, red blood cells. (B) Survival of mice is shown as Kaplan-Meier curves. The experiment was terminated after 365 days. Mean survival, 98 days (VavCre; JAK2^V617F; Cdk6^+/+), 316 days (VavCre; JAK2^V617F; Cdk6^−/−). Log-rank test was used for statistical comparison. *P < .05; ****P < .0001. The group sizes were n (VavCre; JAK2^V617F; Cdk6^+/+) = 23, n (VavCre; JAK2^V617F; Cdk6^−/−) = 23, n (VavCre; Jak2^+/+; Cdk6^+/+) = 10, and n (VavCre; Jak2^+/+; Cdk6^−/−) = 10. (C) Spleen weights at 8 weeks of age are depicted. The group sizes were n (VavCre; Jak2^+/+; Cdk6^+/+) = 19, n (VavCre; JAK2^V617F; Cdk6^+/+) = 15, n (VavCre; JAK2^V617F; Cdk6^−/−) = 13, and n (VavCre; Jak2^+/+; Cdk6^−/−) = 15. Error bars indicate + SD. One-way ANOVA with subsequent Bonferroni posttest was used, and significance is indicated. **P < .01; ****P < .0001.