An overexpression of miR-21 in HCT-116 cells led to the downregulation of PDCD4 and activation of Wnt/β-catenin signaling, along with an increased sphere forming ability in vitro and tumor formation in SCID mice, suggesting that miR-21 may play a key role in regulating stemness in colon cancer cells [27]. The gene discussed is PDCD4; the disease is colonic neoplasm.