CCDC66 and lung adenocarcinoma: Recent studies have found that c-Met activation is in close relationship with the occurrence and development of malignant tumors.9, -11 What’s more, c-Met has been reported to be a new biomarker for pancreatic CSCs.12 It has been reported HGF/c-Met could promote epithelial-to-mesenchymal transition (EMT) in lung adenocarcinoma cells through cirCCDC66 indicating the important role of HGF/c-Met/circ-CCDC66 in cancers.4 What’s more, c-Met has been reported to promote bone metastasis development induced by renal CSCs and enhance the CSCs factors expression in colon cancers.13, -15