BCR and chronic myelogenous leukemia, BCR-ABL1 positive: In CML, miR-451 expression is associated with favorable prognosis, as this miR targets ABL and BCR-ABL directly.66 In contrast, miR-21 is abundantly expressed in various solid and hematologic tumors.67 Investigating miR-21 and miR-451 levels at diagnosis of CML is of great importance as a predictor of optimal TKI response.