FAS and retinal detachment: Fas/FasL signaling was completely eliminated in FasL−/− mice and sFasL was eliminated in ΔCS mice that possess an exchange knock-in mutation in the FasL metalloproteinase cleavage site, producing mice that express increased levels of mFasL and no sFasL.22 The potential neuroprotective effects of sFasL in photoreceptor cell death were also examined during retinal detachment.