The miRNA miR-21 is consistently deregulated in cancers, including lung, glioblastoma and B-cell lymphoma [68–70], and Hatley et al. [71] demonstrated that miR-21 is a potent driver of lung tumorigenesis in a murine model of Kras-induced lung adenocarcinoma. The gene discussed is KRAS; the disease is lung adenocarcinoma.