Cysteine protease that cleaves specifically after arginine residues. Does not cleave caspase-specific substrates. May be involved in the modulation of programmed cell death activated by oxidative stress. Optimum pH is 7.5-8.5 with t-butoxycarbonyl-GRR-aminomethylcoumarin as substrate. By UV-C light, hydrogen peroxide and methyl viologen. Proteolytically processed; by an autocatalytic mechanism. Belongs to the peptidase C14B family.