WT1 and nonpapillary renal cell carcinoma: Niu et al (2005) showed low WT1 transcription levels in ccRCC samples in comparison with tumour-free kidney tissue. By immunohistochemistry Nakatsuka et al (2006) found WT1 protein in four out of twelve (33%) ccRCC samples to be compared with >80% positivity in endometrial and brain tumours. On the basis of these reports and this study the collected data suggest that WT1 can act as a tumour suppressor in ccRCC.