By downloading the cell stemness data corresponding to the TCGA dataset in the relevant literature, we analysed the relationship between JCHAIN and cell stemness indices in BRCA and found that JCHAIN was negatively correlated with mRNAsi and mDNAsi (DNAsi, ENHsi, and EREG-mDNAsi), which indicated that the low expression of JCHAIN promoted breast cancer cell stemness development (Figure 8A–F). This evidence concerns the gene EREG and breast cancer.