CD8A and neoplasm: Also, in mice, Fas ligand-containing exosomes secreted by activated T cells promote tumor invasion in lungs by increasing the expression of matrix metalloproteinase 9 (Cai et al., 2012), and CD8+CD45+ regulatory T cell-released exosomes inhibit CD8+ cytotoxic T-lymphocyte response and antitumor activity (Zhang et al., 2011).