INSR and Insulin resistance: Caffeic acid improves insulin resistance by promoting insulin receptor tyrosyl phosphorylation, upregulating the expression of insulin signaling-associated proteins such as insulin receptors, phosphatidylinositol 3-kinase (PI3K), glycogen synthase, and glucose transporter (GLUT) 2, thereby enhancing glucose uptake in TNF-α-induced insulin-resistant FL83B hepatocytes [77].