Decreased levels of miR-320a in CAF-derived exosomes promote cell proliferation, migration, and metastasis; loss of miR-320a leads to de-repression of its target PBX3, activating MAPK pathway and up-regulation of CDK2 and MMP2; in vivo, miR-320a overexpression suppresses tumor growth and metastasis. The gene discussed is MMP2; the disease is neoplasm.