Lees’ research is focused on identifying the proteins and pathways that play a key role in tumorigenicity and establishing the mechanism of their action in both normal and tumor cells.[1] Her lab at MIT uses a combination of molecular and cellular analyses and mutant mouse models. She is also known for her work with Nancy Hopkins on genetic screens in zebrafish.[4] Lees studies how the E2F family of mammalian transcription factors contributes to the regulation of cellular proliferation during normal development and tumorigenesis.[1] Her work has shown that certain E2Fs, despite substantial biochemical similarities, play radically different biological roles.[5]