MAPK3 and colorectal cancer: miR-143 has been shown downregulation in colorectal cancer tissues to bind to the 3′-UTR of the KRAS gene [28,51], and reduced expression of miR-143 led to cell proliferation in vitro, which is linked to the increased expression of KRAS [51], thus, miR-143, like let-7, acts as tumor suppressor in KRAS-driven colorectal carcinogenesis [29], whereas treating colorectal cancer cells with a miR-143 mimic or overexpressing miR-143 resulted in cell proliferation and downregulation of KRAS and ERK1/2 [51].