Our in vitro findings are strongly supported by the observation that LSC do not depend on BCR/Abl kinase activity for their survival (30), as well as by the clinical evidences that MRD and the related CML relapse following successful IM treatment is usually sustained by cells expressing wild-type BCR/Abl (31). This evidence concerns the gene BCR and chronic myelogenous leukemia, BCR-ABL1 positive.