Rho0 cells do not express mtDNA-encoded COX II protein. Equal amounts of total cell lysates from parental MDA-MB-435 (Lane 1) and Clone 7 Rho0 variant (Lane 2) cells were separated by SDS-PAGE and transferred to a membrane. (A) Blot was hybridized with a monoclonal antibody against cytochrome oxidase II (COXII), and (B) then stripped and rehybridized with a monoclonal antibody against ??-actin. COXII staining demonstrates the loss of expression of the mtDNA-encoded COXII (Lane 2A). Actin staining shows that protein loading is approximately equal (Lanes 1B, 2B).