Recognizes a glycoprotein of ~200kDa, identified as carbonic anhydrase IX (CAIX/gp200). In the normal kidney, gp200 is localized along the brush border of the pars convoluta and pars recta segments of the proximal tubule and 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 help investigate carcinomas of proximal nephrogenic differentiation, especially those showing tubular differentiation