Lipins play important roles in adipogenesis, insulin sensitivity, and gene regulation, and mutations in these genes cause lipodystrophy, myoglobinuria, and inflammatory disorders. While all lipins (lipin 1, 2, and 3) act as phosphatidic acid phosphatase (PAP) enzymes, which are required for triacylglycerol (TAG) synthesis from glycerol 3-phosphate, lipin 1 has been the focus of most of the lipin-related research. In the current issue of the JCI, Zhang et al. show that while lipin 2 and 3 are expendable for the incorporation of dietary fatty acids into triglycerides, lipin 2/3 PAP activity has a critical role in phospholipid homeostasis and chylomicron assembly in enterocytes.