the downregulation of PDGFD, regardless of non-metastatic osteosarcoma or metastatic osteosarcoma, led to a significant upregulation of matrix metallopeptidase 9(MMP9), β-catenin, and zinc finger E-box binding homeobox (ZEB) expression, while E-cadherin expression was downregulated (Fig. 8g, i). The gene discussed is PDGFD; the disease is osteosarcoma.