Cell-permeable. A useful negative control for the BET bromodomain inhibitor (+)-JQ1 (Cat.No.2070). (−)-JQ1 enantiomer has no appreciable affinity to BET bromodomains, whereas enantiomerically pure (+)-JQ1 binds to BRD4 bromodomains 1 and 2 with Kd values of ~ 50 and 90 nM, respectively.