ESR1 and breast carcinoma: Furthermore, we calculated the MHC-I signature score across different breast cancer types based on the Cancer Genome Atlas (TCGA) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) databases and found that the MHC-I score was much lower in ER+ (LumA or LumB) and Her2+ breast cancer types than that of Basal-like types (Figure 1A,B).