TLR7 and lung carcinoma: Experiments conducted using human lung cancer in-situ and human lung cancer cell lines (e.g. A549) revealed that two intracellular TLRs namely TLR7 and TLR8 primarily signal the activation of the NF-κB signaling pathway, upregulation of the antiapoptotic protein Bcl-2 and the increase of tumor cell survival and chemoresistance processes (90).