The relationship between protein concentration of lysates from untreated or insulin-treated CHO-IR/IRS-1 cells and the absorbance at 450 nm using PathScan® Phospho-Insulin Receptor β (Tyr1345) Sandwich ELISA Antibody Pair #7823 is shown. CHO-IR/IRS-1 cells (85% confluence) were serum starved overnight and then treated with insulin (100 nM) for 2 min at 37ºC, and then lysed.