Furthermore, in advanced stage and/or high-grade MECs with poor prognosis, cancer cells showed higher expression levels of inhibitors of DNA binding/differentiation protein 1 (Id-1), a key pro-angiogenic transcriptional factor, and lower expression levels of thrombospondin 1 (TSP-1), a key anti-angiogenic protein ligand [6–8]. Here, THBS1 is linked to cancer.