PPAR α, PPAR β/δ and PPAR γ must form a heterodimers with RXR to function in controlling metabolic processes needed to maintain critical regulatory processes. PPARα controls peroxisome proliferation, fatty acid metabolism and lipid homeostasis. PPARβ/δ controls inflammation, fatty acid catabolism, insulin sensitivity and lipid homeostasis. PPARγ controls fatty acid storage, lipid and glucose homeostasis, cellular differentiation, cellular proliferation and apoptosis.