Although several reports highlight antiproliferative and prodifferentiative actions of PPARγ ligands in cancer cell lines and animal models of human neoplastic disease [8], more recent studies illustrating tumor-promoting effects of PPARγ, in particular in colon and breast cancer models, raise considerable concern about the practicability and safety of PPARγ ligands as anticancer drugs [9, 10]. The gene discussed is PPARG; the disease is breast cancer.