TF and cancer: Besides anti-cancer therapeutic drugs, exosomes can also deliver various tumor antigens (Cho et al., 2005), apoptosis-inducing proteins (Hall et al., 2016), nanobodies (Kooijmans et al., 2016), deficient or mutant anti-apoptosis proteins (Aspe et al., 2014), tumor and tissue-specific peptides (Hung and Leonard, 2015), proteasomes (Lai et al., 2012), transferrins, and lactoferrins (Malhotra et al., 2016) into cancer cells for targeting therapy.