TNF and neoplasm: Since TNF-α was reported to be able to confer anti-tumor effects[29] and was also produced by both LPS + IFN-γ–activated and L-MTP-PE + IFN-γ–activated M1-like macrophages during the co-culture (Figure 4, panel C), a role for TNF-α in the inhibition of osteosarcoma cell growth was examined.