Using cBioPortal14,15 and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) datasets,16,17 we determined that, of the top ten underexpressed phosphatases in ER-negative breast cancer, PPM1A (Protein Phosphatase Mg + 2/Mn + 2 Dependent) is the most frequently deleted phosphatases in ER-negative, compared to ER-positive, breast cancer. Here, PPM1A is linked to breast cancer.