ΔCS mice have an exchange mutation in the FasL metalloproteinase binding site that prevents cleavage of mFasL to produce sFasL.22 Conversely, in WT mice, metalloproteinases cleave mFasL to produce sFasL, which reduces the Fas death signaling.13, 17, 22 This suggests that cleavage of FasL to produce sFasL is a protective mechanism to prevent photoreceptor cell death from Fas signaling after retinal detachment. The gene discussed is FAS; the disease is retinal detachment.