It was possible to identify a selective group of phosphatases upregulated only in the ER− ERBB2+ subgroup and not in ER+ (like DUSP6, DUSP10 and PPAPDC1A among others), suggesting a role of these phosphatases in specific BC subtypes, unlike other differentially expressed phosphatases (DUSP4 and ENPP1) that seemed to have a role in multiple BC subtypes. This evidence concerns the gene PLPP4 and breast cancer.