The peroxisome proliferator activated receptors （PPARs） are ligandactivated transcription factors within the nuclear receptor superfamily， which play important roles in adipogenesis， glucose homeostasis andinflammation. Three different isotypes can be distinguished； alpha， beta and gamma. PPAR?， is mainly expressed in adipose tissue and to lesser extent in colon， the immune system and the retina. Whereas PPAR? operates in the catabolism of fatty acids in the liver， PPAR? influences the storage of fatty acids in the adipose tissue and plays a role in adipocyte differentiation. PPAR? binds to DNA as a heterodimer with retinoid X receptor （RXR）， activating expression of target genes after binding ligand.
