HEK-293 cells stably expressing TRPM8 were grown to 70–80% confluence, washed and collected with cold PBS. Cells were harvested and resuspended in 0.25 M sucrose-1 mM triethanolamine (TEA) HCl, with addition of a protease inhibitor cocktail (Roche, Indianapolis, IN), pH 7.4. Plasma membranes were isolated by differential centrifugation. The TRPM8 protein was extracted from plasma membranes with (in mM) 137 NaCl, 5 KCl, 1 MgCl2, 10 Glucose and 10 Hepes, pH 7.4, in presence of 1% Nonidet P40 (Roche) and 0.5% dodecylmaltoside (DDM) (Roche), and the protease inhibitors, upon incubation at 4°C on a shaker with gentle agitation for 2 h.