Described herein are compounds of Formulae (I)-(II), and pharmaceutically acceptable salts, and pharmaceutical compositions thereof. Also provided are methods and kits involving the inventive compounds or compositions for treating or preventing proliferative diseases such as cancers (e.g., lung cancer, large bowel cancer, pancreas cancer, biliary tract cancer, or endometrial cancer), benign neoplasms, angiogenesis, inflammatory diseases, autoinflammatory diseases, and autoimmune diseases in a subject.