Ligandsof PPARγ have been shown to promotedifferentiation and to inhibit cell growth and induce apoptosis in severaltypes of human cancer, including colon cancer [38–40], breast cancer [41, 42],lung cancer [43], prostate cancer [44, 45], gastric cancer [46], liposarcoma[47, 48], and leukaemia [49], supporting a role for PPARγ ligands as potential tumor suppressorsin PPARγ-dependent or -independent manner[50, 51], although several murine models suggest that, under certaincircumstances, PPARγ ligands may stimulate cancer formation[36]. This evidence concerns the gene PPARG and lung cancer.