In HCC, gut microbial metabolites, including lipoteichoic acid (LTA) and DCA, upregulate cyclooxygenase-2 (COX-2) expression via toll-like receptor 2 (TLR2) on the membrane surface of tumor cells, which increases prostaglandin E2 (PGE2) expression. The gene discussed is TLR2; the disease is neoplasm.