CA6 and rhabdomyosarcoma: To further investigate which stage of C15 functions on CA6 and EVD68 infections, we designed three assays as follows: (i) C15 pretreatment in which C15 was added to rhabdomyosarcoma (RD) cells for 4 h before EV attachment, (ii) incubation treatment in which C15 and EVs were incubated for 4 h in vitro before being added to RD cells, and (iii) post-entry treatment in which RD cells were infected with CA6 or EVD68 for 2 h before C15 was added (27) (Fig. 4A).