TLR9 and hepatocellular carcinoma: Here we for the first time demonstrate that increased mitochondrial fission significantly induces cytosolic mtDNA stress in HCC cells and present a critical finding that mitochondrial fission-induced mtDNA stress promotes the TAM infiltration and HCC progression by activating TLR9-mediated NF-κB signaling pathway to increase the production of CCL2 (Fig. 7).