RAB22A and osteosarcoma: The fusion genes act as oncogenic driver in numerous human cancers.35,36 Exosome derived from tumor cells has been linked to tumor initiation and progression.37 In this report, we demonstrate for the first time that osteosarcoma cells harboring RAB22A-NeoF1 fusion gene, a driver of metastasis, may secrete the Rab22a-NeoF1 enclosed exosomes into tumor microenvironment to affect the functions of their surrounding recipient cells, such as macrophages and tumor cells negative for RAB22A-NeoF1.