MLH1 and lung cancer: Some reports have also shown that oncomir miR-21 downregulates hMSH2 gene expression by targeting the 3′ untranslated region of its mRNA [45], and that miR-155 can significantly downregulate hMSH2, hMSH6, and hMLH1 [46], while others have suggested that miRNAs play an important role in modulating cell cycle progression by targeting hMSH2 in lung cancer [42].