Insulin receptor–PI3K–Akt pathway

The **Insulin receptor–PI3K–Akt pathway** is a critical intracellular signal transduction cascade activated primarily by the hormone insulin and related growth factors. Upon insulin binding, the insulin receptor (a transmembrane tyrosine kinase) undergoes autophosphorylation and activates insulin receptor substrate (IRS) adaptor proteins, which recruit and activate PI3K at the plasma membrane. Activated PI3K generates the lipid second messenger PIP3, leading to the recruitment and activation of Akt (protein kinase B) through phosphorylation events. Activated Akt regulates a wide range of cellular processes including glucose transport (e.g., via GLUT4), protein synthesis, cell growth, proliferation, survival, and metabolism. Dysregulation of this pathway is implicated in numerous diseases, including type 2 diabetes mellitus (via insulin resistance), obesity, and a wide spectrum of cancers where the pathway is often overactive or mutated[1][2][3][5]. Drugs target different nodes within the pathway for the treatment of cancer (PI3K/Akt inhibitors) or metabolic disorders (insulin, metformin), but pathway targeting presents substantive therapeutic and safety challenges due to its central role in normal cell biology.

Other names

Insulin signaling pathwayPI3K/Akt signaling pathwayInsulin receptor signaling cascade

Agonist (for insulin receptor: insulin and mimetics) Kinase inhibitor (for PI3K and Akt: small-molecule inhibitors block ATP binding and kinase activity[5]) Allosteric modulator (certain investigational drugs) Antibody inhibition (for selected receptor tyrosine kinases upstream) Downstream modulation (indirect inhibition by agents like metformin via AMPK activation)