KRAS and cancer: In clinical specimens, we found that miR-4689 was significantly down-regulated in human CRC samples compared with those of normal mucosa samples; moreover, miR-4689 expression was much lower in cancer tissues that harbored mutant KRAS compared with those that harbored wild-type KRAS. Moreover, mechanistic studies showed that overexpression of KRAS gene decreased miR-4689 expression in HEK293 and MRC5 cells (see Supplementary Figure S2b), and that knockdown of KRAS gene in DLD1 induced miR-4689 expression (see Supplementary Figure S3a).