FACS analysis revealed that absolute numbers of Tregs and the frequency of Tregs among CD4+ T cells in the BM of CML mice were significantly increased compared with BM of naive mice (Figure 1E and Supplemental Figure 1, A and B; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.151797DS1). This evidence concerns the gene CD4 and chronic myelogenous leukemia, BCR-ABL1 positive.