SRXN1 contributes to oxidative stress resistance by reducing cysteine-sulfinic acid formed under exposure to oxidants in the peroxiredoxins PRDX1, PRDX2, PRDX3 and PRDX4. It does not act on PRDX5 or PRDX6. SRXN1 may catalyze the reduction in a multi-step process by acting both as a specific phosphotransferase and a thioltransferase.