AKT1 and obesity due to melanocortin 4 receptor deficiency: To determine which LPA receptors are expressed specifically in adipocytes and whether LPA receptor expression is altered under conditions mimicking obesity-insulin resistance, we incubated 3T3-L1 adipocytes with media containing high glucose (30 mM) and high insulin (100 nM) concentrations for 24 h to induce insulin resistance as previously demonstrated [24] and determined by blunted insulin-stimulated Akt phosphorylation at Ser473 (S1 Fig).