Glial production of TNF and expression of its death receptor (TNF receptor-1, TNF-R1) on RGCs and their axons are known to be upregulated in the retina and optic nerve of glaucoma patients and animals with experimentally induced glaucoma [43, 58, 59] and may induce RGC death via multiple mechanisms (Figure 5). The gene discussed is TNF; the disease is glaucoma.