Ac-IEPD-pNA is a colorimetric substrate for granzyme B and caspase-8.1,2 Granzyme B and caspase-8 preferentially bind to and cleave the Ile-Glu-Pro-Asp (IEPD) peptide sequence to release p-nitroanilide (pNA), which can be quantified by colorimetric detection at 405 nm as a measure of granzyme B and caspase-8 activity.WARNING This product is not for human or veterinary use.