An intraocular injection of TNFΑ activates NFΚB in Müller cells. cis-NFΚBEGFP reporter mice underwent optic nerve crush and were analyzed for enhanced green fluorescent protein (EGFP) expression as an indicator of NFΚB activation. EGFP was not detected in control eyes (A), nor was it detected at 1, 3, 5, 7, or 14 days after crush injury (B); thus optic nerve injury and the resultant RGC death does not cause retinal NFΚB activation. In contrast to this, while an intravitreal injection of PBS did not activate NFΚB in the retina (C), there was robust activation of NFΚB as early as 1 day after an intravitreal injection of 100 ng TNFΑ (D). EGFP (green) was present through the retina from the ganglion cell layer (GCL) to the outer limiting membrane, consistent with NFΚB activation in Müller cells. (E-G) NFΚB activity (EGFP expression) co-labeled with the Müller cell marker SOX9 (red, asterisk). NFΚB was not expressed in cells absent for SOX9; however, some SOX9+ cells did not show activated NFΚB (arrow). Sections were counterstained with 4’,6-diamidino-2-phenylindole (blue). Scale bars (D) =50 μm and (G) =10 μm; n ≥3 for each treatment at each time point. INL, inner nuclear layer; ONL, outer nuclear layer.