Ready-to-use colorimetric substrate for caspase-2/Ich-1 and related caspases that recognize the amino acid sequence VDVAD. Caspase-2 and related caspase activity can be quantified by detection of free pNA after cleavage from the peptide substrate VDVAD-pNA at OD405 nm using a spectrophotometer or plate reader. The ready-to-use caspase substrate provides an economic alternative for researchers who perform large amount of caspase assays.