RAB22A and osteosarcoma: In this study, we found that the osteosarcoma Rab22a-NeoF1 fusion protein is secreted into exosomes by binding to HSP90 via its KFERQ-like motif, which is taken up by macrophages and cancer cells negative for this fusion gene, and that the exosomal Rab22a-NeoF1 fusion protein can promote its negative recipient cancer cells to metastasize to lungs in mice through the activation of RhoA by its binding partner PYK2 from donor cells.