ABCB1 and leukemia: Fig 5 depicts such an experiment in which, on the same ELISA plate, samples of a digest of leukemia cells (from patient ME) were assayed for MDR1 using the P3 peptide and the appropriate polyclonal antibody and, in parallel, were assayed for the Na, K-ATPase using the P4 peptide and appropriate polyclonal antibody.