HDAC1 and acute myeloid leukemia: Using a novel hydroxamic acid immobilised resin (HAIR) approach Sinatra et al. were able to synthesise PROTAC 3, which was capable of degrading HDAC1 at a concentration of 10 μM in the acute myeloid leukaemia HL-60 cell line (Chart 1).57 However, HDAC6 was also degraded with 3 and even more effectively degraded than HDAC1 at lower concentrations.