ENPP2 and obesity due to melanocortin 4 receptor deficiency: This article complements prior reviews on the role of the ATX-LPA signaling axis in obesity and impaired glucose homeostasis [9,32] while including many more recent studies and expanding the scope to discuss the involvement of LPP3 in glucose homeostasis and the ATX-LPA-LPP3 axis in metabolic cardiomyopathy.