We investigated the effects of the LSD1 inhibitor tranylcypromine (1, Additional file 1: Figure S1) which is currently under investigation in clinical trials for acute myeloid leukaemia (http://www.clinicaltrials.gov) and a set of five second-generation tranylcypromine analogues (2–6, Additional file 1: Figure S1) with improved target affinity in biochemical enzyme assays. The gene discussed is KDM1A; the disease is acute myeloid leukemia.