HDAC9 and primary cutaneous T-cell non-Hodgkin lymphoma: The histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) has been approved for patients with cutaneous T-cell lymphoma.3 Recently, it was discovered that 3-deazaneplanocin A (DZNep) inhibits EZH2, which has H3K27 trimethylation activity.4 Although SAHA is widely accepted as an HDAC inhibitor, it has been reported to suppress EZH2 expression in cancer cells and to exert an anticancer effect, indicating that SAHA also functions as an EZH2 inhibitor.5, 6