Tissue Homogenate1. Prior to dissection, either perfuse or rinse tissue with phosphate bufferedsaline (PBS), pH 7.4, to remove any red blood cells and clots.2. Homogenize the tissue in 5-10 ml of cold 20 mM HEPES buffer, pH 7.2,containing 1 mM EGTA, 210 mM mannitol, and 70 mM sucrose per gramtissue.3. Centrifuge at 1,500 x g for five minutes at 4°C.4. Remove the supernatant for assay and store on ice. If not assaying on thesame day, freeze the sample at -80°C. The sample will be stable for at leastone month.