MKI67 and melanoma: Compared to PBS control or sEVS345A, treatment with sEVWT and sEVS345D from both human and mouse melanoma cell lines significantly inhibited CD8+ T cell proliferation and activation, as assessed by their expression of Ki-67 and Granzyme B (Fig. 4d, e and Supplementary Fig. 8b–e; Supplementary Fig. 9a).