TTF1 and pleural mesothelioma: One author evaluated IHC expression of TTF-1, E-Cadherin, BG8, WT1 (commercially available polyclonal antibody) and CD44S in pleural mesothelioma, as compared to pulmonary and non-pulmonary adenocarcinomas, of which 10 RCCs (five primary and five metastatic to the lung), and found all RCC cases were negative for WT1 nuclear staining [62].