IRS1 and thymus lymphoma: After binding to its ligand, the insulin receptor is phosphorylated on tyrosine residues and can recruit its two substrates: Insulin Receptor Substrate 1 and 2 (IRS1 and IRS2), which are themselves phosphorylated on tyrosine residues and serve as adapters to initiate several transduction cascades, through the kinases: Phosphoinositol-3 Kinase (PI3K), Akt (mouse Ak strain with thymic lymphoma; also known as Protein Kinase B (PKB)), and mammalian Target of Rapamycin (mTOR).