PNPLA2 and obesity due to melanocortin 4 receptor deficiency: Adipose triacylglycerol lipase (Atgl) that selectively performs the first step in TAG in the liver is reduced in several rodent models of obesity, and Atgl ablation leads to steatosis, although increased TAG content in the hepatocytes from Atgl-deficient mice does not enhance insulin sensitivity [58, 59].