GPX1 and prostate carcinoma: First, GPX1 was downregulated in TetSBP1 tumors (Fig 4), consistent with those observed in human prostate cancer tissues [26], but it was different from the in vitro studies which showed that overexpressing SBP1 did not affect GPX1 protein levels in HCT116 cells although GPX1 activities were significantly downregulated [6].