On the other hand, despite the upregulation of CD26 expression in KMS11, its cytotoxic effect was not sufficiently clear following treatment with several class Our results demonstrated that the cell surface CD26 expression in KMS26, 27, 28, and RPMI8226 was upregulated in parallel to anti-myeloma cytotoxicity on treatment with HDACi. This evidence concerns the gene DPP4 and plasma cell myeloma.