TLR9 and cancer: The main and most studied anti-cancer effect of CQ and HCQ is the inhibition of autophagy, but other preclinically proven anti-cancer activities of the antimalarial agents include influencing the TLR9/nuclear factor kappa B (NF-κB) signalling pathway, the CXCL12/CXCR4 signalling pathway and the p53 pathway.