IGF1R and neoplasm: Binding of IGF to insulin-like growth factor receptor (IGF1R) activates IRS–PI3K–AKT–mTORC1/2 and RAS–RAF–MEK–ERK cascades, promoting cell-cycle progression; protein, lipid, and nucleoside synthesis; inhibition of apoptosis; increased glucose uptake; and metabolic plasticity, collectively driving tumor growth and drug resistance (27).