MTOR and osteosarcoma: Several studies have shown that ET1 increases the activation and expression of MMP2, -9 and -13 in colon cancer, chondrosarcoma, osteosarcoma, and glioblastoma cells via focal adhesion kinase (FAK), phosphatidylinositol 3-kinase (PI3K), AKT, mammalian target of rapamycin (mTOR), and NF-κB [69–72].