TNF and Carcinoma, Lewis Lung: When produced by lung lewis carcinoma tumor cells, versican acts as a ligand for TLR2 and TLR6 expressed by macrophages, generating a strong TNFα response from these cells, and ultimately acting as a help for metastasis (60), via mechanisms that could include TNFα-dependent stimulation of cancer cells proliferation, intravasation and extravasation.