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. EA.hy926 (umbilical vein endothelial cells), were grown to 80-90% confluency, then treated with 1mM pervanadate, a general inhibitor of protein tyrosine phosphatases, for 15 minutes at 37°C.