TNF and carcinoma: Further studies have indicated that the second messenger cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) can translocate from carcinoma cells into astrocytes via CX43-mediated cell–cell junctions, activate the STING pathway to increase their reactivity, and produce inflammatory factors such as interferon-α (IFN-α) and tumor necrosis factor (TNF) [20].