ABCB1 and cancer: It has been confirmed by luciferase activity analysis that miR‐9 can direct bind to the 3′UTR of ABCB1 and then trigger its decay in cancer cells.26 As a transcription factor, ERRα might occupy the conserved ERRE in the promoter of miRNAs and then regulate their expression.41 The mechanisms that XCT‐790 induced up‐regulation of miR‐9 should be further investigated in the future.