3-?(4-?Methoxyphenyl)?-?5-?[(5-?nitro-?2-?thienyl)?methylene]?-?2-?thioxo-4-?thiazolidinone is a protein disulfide isomerases (PDI) inhibitor. PDIs are involved with protein folding in the endoplasmic reticulum. PDI inhibitors are potential anticancer agents.