In contrast, in the presence of HDACi, c-Myc was shown to be dissociated from Sp1 and its binding was replaced by acetylated c-Myc on K323 on the CD26 promoter of myeloma cells, leading to activation of the promoter and initiation of CD26 transcription (Fig. 5D and E). Here, DPP4 is linked to plasma cell myeloma.