TLR9 and neoplasm: Furthermore, TLR-9 is highly expressed in many tumour-derived cell lines, including HeLa cells, and the treatment of HeLa with CpG-ODN stimulates the secretion of chemokine monocyte chemoattractant protein-1 (MCP-1), indicating that TLR-9-dependent signalling pathways are functional in this cell line [67].