TLR7 and lung cancer: Interestingly, the TLR family seems to be quite importantly present in the inflammatory response prior to PMN formation, not only TLR2 as well as TLR3 above, but also other studies have confirmed that exosomal miR-21 and miR-29a secreted by lung cancer cells can bind to mouse TLR7 (Toll-like receptor 7) and human TLR8 (Toll-like receptor 8) in immune cells, inducing TLR-mediated inflammatory responses, which may eventually provide the right conditions for tumor metastasis (22).