PPARD and neoplasm: Surprisingly, GW501516 was found to have a tumor-promoting function in preclinical animal models [6,7,8], and fatty acids in high-fat diets (e.g., arachidonic acid, linoleic acid (LA), and palmitic acid (PA)), serving as natural activating ligands of PPARD [9,10], transformed APC-mutant progenitor cells and promoted colorectal tumorigenesis [6].