No study had specifically investigated the role of miR‐21 in chemoresistance in AML patients, but Bai et al found in 2011 that miR‐21 overexpression in AML cell lines induced daunorubicin resistance in K562 by targeting PTEN. 29Li et al30 reported that miR‐21 inhibition sensitizes AML cell lines to cytarabine by inducing apoptosis. This evidence concerns the gene PTEN and acute myeloid leukemia.