BRD4 and breast cancer: Given that PRMT2/4 and BRD4 are commonly overexpressed in breast tumors and play a crucial role in breast cancer progression (50–52), we next investigated whether PRMT2/4-mediated methylation of BRD4 at 3R regulates its oncogenic function using two common breast cancer cell lines, MCF7 and MDA-MB-231, that have been frequently used in PRMT4- and BRD4-relevant studies (52–55).