Recognizes a glycoprotein of ~200kDa, identified as carbonic anhydrase IX (CAIX/gp200). Its epitope resides in the carbohydrate domain of gp200. It shows no significant cross-reactivity with other carbohydrate determinants, such as the Lewis blood group antigens, epithelial membrane antigen, HMFG, and AB blood group antigens. In normal kidney, gp200 is localized along the brush border of the pars convoluta and pars recta segments of the proximal tubule, as well as focally along the luminal surface of Bowman’s capsule adjoining the outgoing proximal tubule. Reportedly, gp200 is expressed by 93% of primary and 84% of metastatic renal cell carcinomas. This MAb may be useful in the investigations of carcinomas of proximal nephrogenic differentiation especially those showing tubular differentiation.