Microarray analyses suggest that HDAC inhibitors can alter the transcription of as many as 7–10% of genes (using a 2-fold change as the cut-off value) in cell lines from patients with leukemia, multiple myeloma, and carcinomas of the colon, bladder, kidney, prostate, and breast [51]–[55]. The gene discussed is HDAC9; the disease is plasma cell myeloma.