In light of this finding and considering that the expression of both MR and RARB are reduced in breast cancer, we investigated the intrinsic subtype-specific expression level of MR, RARA, RARB and RARG in breast cancer cases from the METABRIC dataset, based on the PAM50 signature classification [33], to gain insight into the prevalence and subtype of breast cancer cases where MR and RAR signalling may be activated. This evidence concerns the gene RARG and breast cancer.