A subset of extracellular miRNAs has been reported as ligands for the TLR family sensing viral single-stranded RNAs, which in turn prompted us to hypothesize that EV-loaded let-7b activates the TLR7 signal in endosomes of recipient cells to promote inflammatory responses in the central nervous system (CNS)/brain and cancer cells (Buonfiglioli et al., 2019; Fabbri et al., 2012; Lehmann et al., 2012). This evidence concerns the gene TLR7 and cancer.