Distribution of the 140-kDa WND product, cytochrome c oxidase, and Na,K-ATPase in HepG2 membrane fractions. HepG2 homogenate was centrifuged and membrane fractions were collected. Thirty micrograms of protein from each fraction was separated by 7.5% Laemmli gel and immunostained with anti-cytochrome c oxidase antibody (aCOX), aC-WND, or antibody directed against Na,K-ATPase.