Pan-HDAC inhibitors have been reported to elevate PRDM1 expression levels in follicular lymphoma cells (33), and we also found that another pan-HDAC inhibitor, PCI-24781, could elevate PRDM1 expression levels in T cell acute lymphoblastic leukemia (T-ALL) cells. This evidence concerns the gene HDAC9 and T-cell acute lymphoblastic leukemia.