The reduction in let‐7 in cancer tissues is correlated with higher KRAS mRNA expression; and let‐7 miRNA suppressed colon cancer growth and proliferation.79 miR‐143 has been also shown down‐regulated in CRC tissues, and reduced expression of miR‐143 led to cell proliferation in vitro, which is linked to the increased expression of KRAS.66 In contrast, miR‐31 has been shown to negatively regulate KRAS inhibitor RASA1; thus, miR‐31 could be a potent enhancer of KRAS in CRC. This evidence concerns the gene KRAS and cancer.