In contrast, in the presence of HDACi, c-Myc is detached from the CD26 promoter via Sp1 with the increased acetylation of c-MycK323 and the promoter is thereby activated, leading to initiation of CD26 transcription as well as activation of cytotoxicity in several myeloma cells (Fig 5F). This evidence concerns the gene DPP4 and plasma cell myeloma.