Several studies have demonstrated that, compared to their normal counterparts, the expression of PPARγ in tumour cells is either overexpressed, such as in renal cell carcinoma (Inoue et al, 2001) and testicular cancer (Hase et al, 2002), underexpressed, such as in oesophageal carcinomas (Terashita et al, 2002) or is equal to the normal tissue, such as in colonic adenocarcinomas (Sarraf et al, 1998). This evidence concerns the gene PPARG and neoplasm.