As our single-cell RNA-seq (scRNA-seq) analyses revealed Gpx2 overexpression in cancer stem cells (Fig. 3g,h), we probed its functional relevance by adding the glutathione peroxidase inhibitor tiopronin28 to the basal medium reservoirs of mini-colons right after blue-light-induced AKP mutagenesis (Fig. 4a). This evidence concerns the gene GPX2 and cancer.