LSD1/HDAC-IN-1 (compound 2) is a potent inhibitor of HDAC and LSD1 , with IC 50 s of 0.125 nM, 0.373 nM, 0.0118 nM, 0.103 nM, and 0.571 μM for HDAC1 , HDAC2 , HDAC6 , HDAC8 and LSD1 , respectively. LSD1/HDAC-IN-1 plays an important role in cancer research.