Interestingly, ovaries injected with mESC-HrasV12/SV40 LTg also formed mature teratomas, but in addition revealed parts of an immature teratoma containing scattered foci of a high-grade malignant neoplasm, characterized by malignant cells arranged linearly, in small clusters, and occasionally as rudimentary gland-like structures (Fig 6A-(c) small window). The gene discussed is TNFSF14; the disease is teratoma.