LSD1/2-IN-4, a PCPA derivative, is an inhibitor of lysine-specific demethylase 1 (LSD1) and lysine-specific demethylase 2 (LSD2). LSD1/2-IN-4 inhibits LSD1 and LSD2 with K i values of 0.11 μM and 130 μM, respectively. LSD1/2-IN-4 can be used for the research of several cancers including T-cell acute lymphoblastic leukemia (TALL).