Interestingly, there was a report that drug resistant multiple myeloma cells were selectively isolated by CDy1 as a dim population of staining, and the molecular target was identified as ABCB1, one of the ATP-binding cassette (ABC) transporters.8 To evaluate the possible role of transporters in CDy1 selectivity, we checked the CDy1 staining pattern on mESC and MEF under fixed or unfixed condition (Fig. S5, ESI†). The gene discussed is ABCB1; the disease is plasma cell myeloma.