So both eukaryotic cells and prokaryotic cells, such as bacterial cells actually have ABC transporters but usually there are two important differences. So number one, eukaryotic cells usually contain ABC transporters that consist of a single polypeptide chain, a single polypeptide subunit, as we saw in the case of the MDR protein. So MDR proteins, found on the membrane of human cancer cells basically is a single polypeptide chain. Even though we have these four different regions within that polypeptide chain, it's only a single subunit. But prokaryotic cells typically express ABC transporters that contain many subunits. So sometimes we have dimers, sometimes we have tetrimers and so forth.