HEXIM1 and breast carcinoma: Our data are in line with results obtained after knockdown of MEPCE in HeLa, HEK293 and breast cancer cell lines causing a decrease in the steady-state level of the 7SK snRNA, depletion of LARP7 protein, and diminished interaction between HEXIM1 and Cyclin-T1, concomitantly leading to a destabilized 7SK snRNP complex25,28,37.