Overoxidation of Prx2 and Prx1 by H2O2in vivo. Proteins extracted from the cells, after being exposed to various levels of H2O2 for 5 min as indicated, were resolved on nonreducing (upper panels) or reducing SDS-PAGE (lower panels). Immunoblotting was conducted using rabbit anti-Prx2 (A, upper panel), anti-Prx1 (B, upper panel), anti-Prx2-CP-SO3H (A, lower panel), and anti-Prx1-CP-SO3H (B, lower panel) antibodies as indicated. The protein size markers (Bio-Rad) are in kilodaltons. prx2, prx2 mutant; prx1, prx1 mutant; ▵, dimeric Prxs; ▾, overoxidized monomeric Prxs.