PX-12(IV-2) is an irreversible inhibitor of Thioredoxin-1(Trx-1) currently in clinical development as an antitumor agent; IC50=7 uM in Hela, MTT assay, 72 h.Based on MTT assays, PX-12 inhibited the growth of HeLa cells with an IC50 value of ~7 μM at 72 h.