RAB22A and osteosarcoma: Since Rab22a-NeoF1 only occurs in a subset of cancer cells, we sought to mimic the heterogeneous osteosarcoma tumors in mice by orthotopically injecting U2OS/MTX300-luc cells alone or together with either ZOS-M-shNC or ZOS-M-shRAB22A-NeoF1 at both the 10:1 and 10:2 ratios.