The results revealed that inoculation of EVs more strongly stimulated T cell differentiation to activate cellular immune response and inflammation compared to CM.23,31,35 We then tested effector memory T (EMT) cells in the treatment group.60 The main mechanism by which EV–CM can effectively prevent melanoma is that it significantly enhances the activation of EMT (CD3+ CD8+ CD44+ CD62L−) (Fig. 3j, k). Here, CD44 is linked to melanoma.