The Smurf2 protein may help suppress tumors by protecting DNA from damage. This image of of osteosarcoma cells shows undamaged DNA (blue) and sites of DNA damage (red) in the cell nucleus. Smurf2 protein (green) is localized to the damaged DNA. E3 ubiquitin-protein ligase SMURF2 is an enzyme that in humans is encoded by the SMURF2 gene. An osteosarcoma is a cancerous tumor in a bone. Specifically, it is an aggressive malignant neoplasm that arises from primitive transformed cells of mesenchymal origin (and thus a sarcoma) and that exhibits osteoblastic differentiation and produces malignant osteoid. Osteosarcoma is the most common histological form of primary bone cancer. It is most prevalent in children and young adults.