Four of the top 20 genes are upregulated in cancer stem cells, including Id3 in cancer stem cells of a mouse mammary tumor model [58] and ID3 in intrahepatic cholangiocarcinoma tumors [83]; MGST1 in human pancreatic cancer stem cells [84]; and GPX3 and GSN in quiescent colon cancer stem cells [85]. The gene discussed is GPX3; the disease is breast cancer.