Fig. 2

The function of TSPANs in EV biogenesis. TSPANs can regulate the biogenesis of EVs in the following aspects: (1) TEMs are prone for internalization or curvature [106, 107], and proteins in TEMs have been proposed to be carried by EVs [108]; (2) TSPANs contribute to EE traffic towards MVB [109]. (3) The exosome TSPAN web strengthens binding avidity by clustering TSPAN-associated molecules. TSPAN8 could promote EV production and the attachment to target cells. In contrast, TSPAN6 can reduce EV production and the contents in EVs in cancer cells. CD151 facilitates secretion of ribosomal proteins while reducing complement proteins to promote the migration and invasion of triple-negative breast cancer cells [111]. CD81 ensures the membrane integrity of exosomes, which are capable of inducing stemness in triple-negative breast cancer [18]. CD9 on the surface of EVs facilitates the uptake of EVs from cancer-associated fibroblasts by pancreatic cancer cells [117]