INSR and Insulin resistance: A variety of these lipid species, including diacylglycerides (DAGs), free fatty acids (FFAs), sphingolipids, and ceramides, can contribute to insulin resistance by stimulating various serine/threonine kinases, including members of the novel PKC family, resulting in increased serine/threonine phosphorylation of the insulin receptor (IR) substrates IRS1 and IRS2, the IR, and other proteins, which collectively lead to decreased insulin action (18, 19).