PDGFD and osteosarcoma: To verified the findings based on scRNA-seq data, IHC was used to detect PDGFD and PDGFRB expression in non-metastatic and metastatic osteosarcoma primary lesions, and found that PDGFD was mainly expressed in osteosarcoma cells, while the PDGFRB expression was observed in both osteosarcoma cells and stromal cells.