Given the significantly downregulated expression level of EZH1 protein in TNBC, the authors subsequently analyzed the downregulation level of EZH1 in BC subgroups, and it was found that EZH1 protein was lowly expressed in TNBC tissue compared with normal breast, HER2-positive, or luminal BC tissue (Fig. S2). This evidence concerns the gene ERBB2 and breast cancer.