IRS4 and neoplasm: The IRS protein cascades are the most valuable protein cascades in the insulin signaling pathway, including IRS-1, IRS-2, IRS-3, IRS-4, IRS-5, and IRS-6 [11], of which, IRS-1 and IRS-4 are most associated with tumor growth and proliferation, and IRS-2 is the most frequently associated with tumor movement and invasion [12].