TXN and diffuse large B-cell lymphoma: PX-12 specifically inhibits Trx-1 by irreversibly thio-alkylating the Cys73 residue of Trx-1.[16, 17] PX-12 inhibition of Trx-1 has previously shown both excellent in vitro antitumor activity and promising in vivo antitumor activity in solid tumors.[18, 19] To test the efficacy of PX-12 in DLBCL cells, we exposed 18 DLBCL cell lines, including the Dox-resistant cell line McA-DR, to increasing concentrations (0–50 μM) of PX-12 and then analyzed cell proliferation using thymidine incorporation assays.