KLF4 and chronic myelogenous leukemia, BCR-ABL1 positive: Although no significant alterations in cell proliferation and apoptosis were observed, analysis of purified CML LSCs (Lin−Sca-1+c-Kit+BCR-ABL1+) using two gold-standard assays to evaluate the self-renewal capacity of malignant HSCs revealed the inability of these cells to serially generate colonies in methylcellulose cultures and, most importantly, to recapitulate leukemia upon transplantation into secondary hosts, suggesting that loss of KLF4 severely abrogates self-renewal capacity.