LSD1 demethylates TIP60 methylation. (A) Cell extracts from HCT116 cells were immunoprecipitated with anti-TIP60 antibodies. Immunoprecipitates were eluted, resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), and immunoblotted with the indicated antibodies. (B) HCT116 cells were treated with 500 nM GSK-LSD1 for 24 h. IPs using an anti-methyl lysine antibody were performed. Methyl lysine levels were normalized by input of TIP60. (C) HCT116 cells were transfected with Flag-EV of Flag-LSD1 and treated with 5 mM HU for 4 h. IPs using an anti-methyl lysine antibody were performed. Methyl lysine levels were normalized by input of TIP60. (D) Flag-LSD1, Flag-TIP60 WT, or Flag-TIP60 K137R were subjected to the homologous recombination (HR) assay. Results were shown as the mean ± SEM; n = 5, ***P < 0.001, N.S: no significant difference.