GPX1 and breast cancer: We also showed, in both TNBC cell lines and tumor tissues, the inverse correlation between GPX1 and SELENBP1, a protein lacking selenocysteine residues in its sequence but binding exogenous selenium, confirming the correlation of these two proteins previously reported in breast cancer cells, in which SELENBP1 was suggested to play a critical role in modulating the extracellular microenvironment by regulating the levels of extracellular GSH [46].