PDE6B and retinal degeneration: Calpains [EC 3.4.22.17], a group of calcium-dependent cysteine proteases, play some important roles in caspase-independent photoreceptor apoptotic pathways with light-induced retinal damage [19] and in rd1 mice [20, 21] and Royal College of Surgeons (RCS) rats [22] as models of retinal degeneration.