GPX3 and cancer: Thus, in the tumor materials included in this study, we could not confirm any tumor suppressor activity of Gpx3. In the human material highly significant differences in the expression of MET between normal and tumor tissues were found (P < 0.001), but not in the way as would be expected from previous studies, where it was suggested that down regulation of GPX3 causes up-regulation of MET in some cancer types [17-23].