786-O-luc cells transfected with LV-NC, LV-circCYP24A1, LV-circCYP24A1 plus miR-421 mimic, and LV-circCYP24A1 plus sh-CMTM4 were injected into the tail vein of nude mice to explore the lung metastasis ability of RCC cells. Here, CMTM4 is linked to renal cell carcinoma.