Since the FKN ligand is enriched in the ganglion cell layer of the retina in both humans and mice (Silverman et al., 2003; Zieger et al., 2014) including RGCs in the DBA/2J (Supplemental Figure 1), we reasoned that loss of FKN signaling may influence key aspects of RGC decline in glaucoma. The gene discussed is CX3CL1; the disease is glaucoma.