In 2017, Rusolo et al. compared seleno-transcriptome expression between the human non-cancerous mammary epithelial cell line MCF-10A and two human breast cancer cell lines, MCF7 and MDA-MB-231, and identified four downregulated genes, GPX1, GPX4, GPX5 and GPX7, and three upregulated genes, iodothyronine deiodinase 2 (TXDI2), GPX2 and GPX3, in breast cancer cells. The gene discussed is GPX1; the disease is breast cancer.