Johnson et al. explored the mechanistic role of let-7 in human lung cancer cells and found that overexpression of let-7 inhibited lung cancer cell proliferation by negatively regulating the expression of RAS [22] and altered cell cycle progression by repressing multiple genes involved in the cell cycle, including CDK6 and cell division cycle 25A (CDC25A) [23]. The gene discussed is CDK6; the disease is lung carcinoma.