Generation of HPC^LSKcell lines from Cdk6^−/−mice. (A) Cell proliferation curve of HPC^LSKCdk6^+/+ and Cdk6^−/− cell lines. Data are presented as mean ± SEM of 3 different cell lines per genotype. (B) Colony formation assay of HPC^LSKs BCR/ABL^p210Cdk6^+/+ and Cdk6^−/−. Representative macroscopic images of colonies formed within 7 days in semisolid methylcellulose gels without cytokines are depicted. Data are presented as mean ± SEM of 2 independent experiments with 2 to 3 different cell lines per genotype. (C) Top: Schematic representation of the experimental setup; bottom: HPC^LSKs BCR/ABL^p210Cdk6^+/+ and Cdk6^−/− have been injected IV in NSG recipient mice. Disease-free survival following IV injection of 1 × 10⁶ HPC^LSKs BCR/ABL^p210Cdk6^+/+ (n = 9, 3 different cell lines per genotype) and Cdk6^−/− (n = 7, 3 different cell lines per genotype). Statistical differences were calculated using the log-rank test (****P < .0001). (D) Quantification of BCR/ABL^p210 GFP⁺ cells by flow cytometry in BM and spleen of diseased NSG recipient mice. Error bars represent mean ± SEM (n = 7 to 9 per group, 3 different cell lines; *P <.05 by Student t test).