The present invention provides novel compounds of any one of Formulae (I) to (IV), and pharmaceutically compositions thereof. Compounds of any one of Formulae (I) to (IV) are believed to be inhibitors of bromodomain-containing proteins (e.g., bromo and extra terminal proteins (BETs)). Also provided are methods, uses, and kits using the inventive compounds and pharmaceutical compositions for inhibiting the activity of the bromodomain-containing proteins and for treating and/or preventing in a subject in need thereof diseases associated with bromodomain-containing proteins, such as proliferative diseases.