An immediate rationale for the development of BET/Brd4 inhibitors was provided by the discovery of recurrent t(15;19) chromosomal translocations (and the resulting in-frame fusion of Brd4 and nuclear protein in testis [NUT]) as the cause of NUT midline carcinoma (NMC) (Filippakopoulos et al., 2010; French et al., 2001). The gene discussed is BRD4; the disease is nut midline carcinoma.