In an effort to obtain a more integrated understanding of the different breast cancer phenotypes, and to investigate whether bio-molecular profiles can distinguish between the two most common histotypes, we explored the inter-relations among several biologic variables (consolidated or of a more recent acquisition) related to hormone dependence (ER and PgR), proliferative activity potential (thymidine labelling index (TLI), cyclin A), cell-cycle and apoptosis control (p16ink4A, p27kip1, p21waf1, p53 and bcl-2) and angiogenesis (VEGF and hypoxia-inducible factor-1α (HIF-1α)) in IDC and ILC. This evidence concerns the gene PGR and breast cancer.