Effect of pharmacological and transcriptional inhibition of lysine-specific demethylase 1 (LSD1) on cell cycle progression of human microvascular endothelial cells (HMEC-1). (A) The effect of LSD1 shutdown due to 2-phenylcyclopropylamine (2-PCPA) treatment or shRNA transfection on the mitotic index, the induction of aberrations in the M phase of cell cycle and apoptosis (MI, a percentage of mitotic cells in relation to all cells, both interphase and mitotic). The percentages were calculated based on 3000 cells per repeat; (B,D) Flow cytometry analysis of cell cycle. Cells were stained with propidium iodide. The obtained histograms were analyzed using FlowJo software 10.4.1. (“A” stands for the subpopulation of apoptotic cells). Presented histograms are representative of three independent experiments; (C,E) Gene expression profile of cell cycle regulators in HMEC-1 treated with 100 µM of 2-PCPA (E) or after transcriptional LSD1 silencing by specific shRNA (C). Presented data are average of three independent experiments. The level of significance was determined at * p < 0.05, ANOVA and post hoc analysis by Tukey’s test.