In vitro, the abundance of expression of ClC-5 was significantly higher in osteosarcoma cell lines compared with normal osteoblasts hFOB1.19, and even close to that in renal proximal tubule epithelial HK-2 cells (Figures 1E, F), where ClC-5 has been demonstrated to be highly expressed (13). The gene discussed is CLCN5; the disease is osteosarcoma.