We are interested in the mechanisms that control cell fates during development and pathogenesis. We have been focusing our attention on the Notch signaling pathway. Notch signaling defines an evolutionary ancient cell interaction mechanism, which plans a fundamental role in metazoan development. Signals exchange between neighboring cells through the Notch receptor can amplify and consolidate molecular differences, which eventually dictate cell fates. Thus Notch signals control how cells respond to intrinsic or extrinsic developmental cues that are necessary to unfold specific developmental programs. Notch signal modulation was shown to affect the implementation of differentiation, proliferation and apoptotic programs, providing a general developmental tool to influence organ formation and morphogenesis. We have been exploring the molecular biology of notch signaling and its involvement two known human syndromes as well as the onset and maintenance of neoplastic fate.