Despite continuous elevation of TrxR1 activity in MCF-10A cells treated with H2O2, its level in MCF-10AT cells was still clearly lower than basal TrxR1 activity of breast cancer cell line MCF-7 (P < 0.05), which might reflect high-grade malignance of MCF-7 cells. Here, TXNRD1 is linked to breast carcinoma.