SETD4 and breast cancer: Although the aforementioned studies have hinted at an involvement of SETD4 in tumorigenesis, SETD4’s direct role in tumorigenesis has largely been elusive until three recent studies that were conducted with quiescent breast cancer stem cells (qBCSCs) (34), with a mouse model of radiation-induced T lymphoma (46) and with a newly identified non-histone substrate of SETD4 (24), respectively.