-Inhibited the proliferation and survival of both cell lines-Induced the apoptosis of NB4 cells only-Induced the cell cycle arrest in G0/G1 phase-Increased the levels of ATM, HMGA2, phosphorylated ATM, and SA-β-galactosidase staining (indicated that EGCG caused cellular senescence)-Induced beneficial epigenetic modulation of epigenetic players DNMT1, HP1α, H3K9me3, EZH2, and SUZ12 in NB4 cells⇒ EGCG is a promising epigenetic modulator for acute promyelocytic leukemia therapy and as a potential cellular senescence inducer in both acute and chronic myeloid leukemia treatment. This evidence concerns the gene ATM and chronic myelogenous leukemia, BCR-ABL1 positive.