Children with the brain tumor Supratentorial Ependymoma ("ST-EPN") have low survival rates (50% at 10 years) and very high relapse rates (70%). The only effective treatments for ST-EPN are surgery and radiation; sadly, there is no chemotherapy that is known to be effective in this disease. There is a big need for new treatments for ST-EPN, and a need for research to figure out those treatments. Researchers recently discovered that most cases of ST-EPN are caused by a "fusion oncoprotein" called ZRFus, and very little is known about how ZRFus works. I have now developed a new tumor model where the ZRFus has a "tag" on it that allows researchers to identify everything that ZRFus touches in the tumor cell: every protein, every gene that ZRFus targets to cause ST-EPN. To make this model, I start from "induced pluripotent stem cells" (iPSCs, which originally were made from the skin cells of adult humans). In the lab, I grow iPSCs to become brain stem cells, then I add ZRFus, and then I surgically implant those cells-with-ZRFus into the brains of mice. It takes about 3 months, but those implanted cells grow into brain tumors that strongly resemble ST-EPN. Examining the tumors, I can find the ZRFus by its "tag", and find everything that ZRFus is interacting with. Those interactors might be a part of ZRFus's tumor-causing toolkit, and are candidates for future therapeutic targets in clinical trials