sEVs of hypoxic melanoma, squamous skin carcinoma and lung cancer cells are loaded with immunosuppressive proteins like colony-stimulating factor 1 (CSF-1), C-C motif chemokine 2 (CCL2), ferritin heavy chain (FTH), ferritin light chain (FTL) and TGF-β as well as the miRNA let-7a [47]. Here, CCL2 is linked to melanoma.