PPARD and neoplasm: A PPARβ-deficient colon cancer cell line was defective in establishing tumours when grown as xenografts in nude mice (Park et al, 2001a), and the activation of PPARβ by a synthetic ligand in mice pre-disposed to intestinal tumorigenesis (ApcMin mice) resulted in a significant increase in the number and size of intestinal polyps (Gupta et al, 2004).