IRS1 and type 2 diabetes mellitus: Western blotting analysis can be used to measure phosphorylation of the insulin receptor (INSR), insulin receptor substrate-1 (IRS-1) and extracellular-signal-regulated kinases (ERK1/2) in iPSC-derived myotubes, thereby reflecting insulin responsiveness within these cells and their functionality for treatment of IR in T2D [96].