ESR1 and breast cancer: Several studies have demonstrated that EGCG-mediated HDAC inhibition is associated with cell-cycle arrest, apoptosis, and metastasis mediated by upregulation of the genes which suppress cancer pathogenesis including Raf kinase inhibitor protein (RKIP) in pancreatic cancer cells, tissue inhibitor of matrix metalloprotease-3 (TIMP3) in breast cancer cell lines, and estrogen receptor α (ESR1) in ER-negative breast tumor cells (Meeran et al., 2012; Kim & Kim, 2013; Deb et al., 2015).