DPP4 and plasma cell myeloma: We also treated KMS27 and KMS28 with titrated concentrations of with panobinostat (0.5, 5.0, 50, 500 nmol/L), RG2833 (5.0, 50 nmol/L, 0.5, 1.0 μmol/L), and entinostat (0.5, 5, 50, 100 μmol/L) for 48 hours and observed a dose-dependent increase in CD26 expression on each myeloma cell by flow cytometry (Fig. 1C).