Although frequent downregulation of hMOF and overexpression of CA9 were detected in both RCC clinical tissues and RCC cell lines, non-correlation between hMOF and CA9 was found in RCC 786–0 cells, suggesting hMOF and its corresponding modifications might be a new CA9-independent RCC diagnosis biomarker. The gene discussed is KAT8; the disease is renal cell carcinoma.