Cell or tissue lysates are a useful control for the western blotting application. A source that can be rich in endogenously expressed proteins, this lysate is convenient to use and provided in a denatured format allowing for immediate loading onto an SDS-PAGE gel. A431 cells (Human epithelial carcinoma; ATCC CRL-1555) were grown to 80-90% confluency, serum starved overnight, then treated with 100 ng/mL EGF for 5 minutes at 37°C.