Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor subfamily of transcription factors.Three PPAR subtypes, designated PPARα, PPARβ (also designated PPARδ) and PPARγ, have been described. PPARs form heterodimers with retinoid X receptors (RXRs). These heterodimers regulate transcription of genes involved in insulin action, adipocyte differentiation, lipid metabolism and inflammation. Peroxisome proliferator-activated receptor γ (PPARγ) is preferentially expressed in adipocytes as well as in vascular smooth muscle cells and macrophage. Besides its role in mediating adipogenesis and lipid metabolism, PPARγ also modulates insulin sensitivity, cell proliferation and inflammation.