BCR-ABL expression analysis of individual BCR-ABL–positive CFU using PCR. The BCR-ABL expression levels of BCR-ABL–positive CFU from CML-Dx and during MMR are shown, reported as the normalized copy number ratio of BCR-ABL. (A) Each column represents the BCR-ABL expression value of an individual CFU harvested from the indicated subfraction. (B) BCR-ABL expression of all analyzed BCR-ABL–positive CFUs from CML-Dx (gray) versus MMR (dark). Bars represent means ± SEM (***P < .0001, according to Mann-Whitney t test. (C) Comparison of the BCR-ABL expression level of BCR-ABL–positive CFUs from CML-Dx (gray) versus MMR (dark) sorted from bone marrow compartments as indicated. Bars represent mean values ± SEM (***P < .0001; **P < .01; *P < .05). Statistical significance was assessed using a 2-way ANOVA with Bonferroni adjustment for multiple comparisons. (D) BCR-ABL mRNA expression in individual BCR-ABL–positive CFUs (means ± SEM) at initial diagnosis (black) and 3 months after initiation of IM treatment (gray) in individual patients (***P < .0001; **P < .001; *P < .05). Statistical significance was assessed using Kruskal-Wallis test with Dunn multiple comparison test to adjust for multiple comparisons.