IRS1 and Insulin resistance: At the same time, PA significantly decreased the insulin-stimulated glucose transporter-4 (GLUT4) translocation, the protein expression of insulin receptor substrate-1(IRS-1) and insulin signaling molecule AKT phosphorylation, but induced the phosphorylation of insulin receptor substrate-1 at site serine 307 (pIRS-1ser307) to verify insulin resistance in HK-2 cells (Fig. 1c–g).