The exosomal contents can govern various processes of tumor progression such as tumor metastasis (RNAs such as miR-200, miR-99a-5p, and circWHSC1), immune regulation (proteins such as Hsp84/90, MHC I and II, TSG 101, and CD63), and drug resistance (Annexin A3 and miR21; Fig. 2) and discussed in the following sections. The gene discussed is CD63; the disease is neoplasm.