In addition to low expression of ER, PR and HER2, basal-like breast cancers are characterized by a high expression of CK5, CK14, caveolin-1, caix, p63, EGFR (Epidermal Growth Factor Receptor)/HER1, which reflects on the mammary gland basal/myoepithelial cell component [7]. Here, PGR is linked to breast cancer.