BRD4 and leukemia: NSUN1 specifically interacts with BRD4 and then directly binds to RNA-pol-II CTD-S2P to form a unique NSUN1/BRD4/RNA-pol-II CTD-S2P complex in 5-azacitidine (5-AZA)-resistant leukemia cells, thus mediating the formation of a 5-AZA-resistant chromatin structure and inducing 5-AZA resistance in leukemia [18].