IRS1 (Insulin Receptor Substrate 1) is a key signaling protein that helps mediate the body’s response to insulin and growth factors. Acting as an adaptor, IRS1 connects activated insulin receptors to various downstream pathways, regulating processes like glucose uptake, glycogen synthesis, protein production, and cell growth. Dysregulation of IRS1 is linked to insulin resistance, type 2 diabetes, and may also play roles in cancer and cardiovascular diseases.