<jats:p> Background: Elevated expression of CAV1 in breast cancer increases tumor progression. Extracellular vesicles (EVs) from CAV1-expressing MDA-MB-231 breast cancer cells contain Tenascin C (TNC), but the relevance of TNC remained to be defined. Methods: EVs were characterized by nanotracking analysis, microscopy and western blotting. The uptake of EVs by cells was studied using flow cytometry. The effects of EVs on breast cancer cells were tested in migration, invasion, colony formation and in vivo assays. Results: EVs were taken up by cells; however, only those containing TNC promoted invasiveness. In vivo, EVs lacking TNC ceased to promote tumor growth. Conclusion: CAV1 and TNC contained in breast cancer cell-derived EVs were identified as proteins that favor progression of breast cancer. </jats:p>
