Althoughstudies of some cancers, such as lung and breast cancer, have demonstrated thatLet-7 miRNAs directly repress KRAS mRNA (Esquela-Kerscher et al., 2008; Iliopoulos et al., 2009; Johnson et al., 2005),KRAS has not been found to be a Let-7 target in studies ofCRC (King et al., 2011b; Madison et al., 2013, 2015). The gene discussed is KRAS; the disease is breast cancer.