In oral [94], pancreatic [129], breast [130], and colon [131] cancers, miR-21 enhances cancer stem cell survival, proliferation, and invasion by targeting stemness markers, including OCT4, SOX2, CD133, and CD44, as well as signaling pathways such as Wnt and AKT/ERK1/2. The gene discussed is MAPK3; the disease is cancer.