EZH2 and breast cancer: Enhancer of zeste homolog 2 (EZH2), which is a histone H3 (trimethylation of H3 on lysine 27 (H3K27me3)) methyltransferase, is often overexpressed in a number of solid tumors, such as prostate cancer, breast cancer, colorectal cancer (CRC), melanoma, endometrial cancer, and glioblastoma (GBM) [4–6].