BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Indeed, in CML LSCs, miR-126 is downregulated due to the BCR-ABL1-mediated phosphorylation of Sprouty-related EVH1-domain-containing 1 (SPRED1), which leads to inhibition of the RAN-exportin-5-RCC1 complex that mediates miRNA maturation.