We next stratified the dataset into the ER+ and ER− breast cancer samples, but no correlation was found between SOX2 and AXIN2 or DKK1, or between AXIN2 and DKK1 expression in ER+ (Table S4 in Supplementary Material) or ER− samples (Table S5 in Supplementary Material). Here, DKK1 is linked to breast carcinoma.