PDCD1 and breast carcinoma: Characteristically, activated T cells overexpress PD-1 on their surface; so, the use of EVs derived from activated T cells expressing PD-1 is effective in blocking the dysfunction generated by the ligation of PD-L1 expressed by tumor cells, promoting the synthesis of IL-2, IFN-γ and granzyme B in infiltrating T cells in a breast cancer model [162].