Unlike hormone-receptor-positive tumours that express the oestrogen receptor (ER) and progesterone receptor (PR), or HER-2-positive neoplasms that express the erb-b2 transmembrane receptor, triple-negative breast cancers (TNBCs) are negative for all three receptors (Nielsen et al., 2004; Prat et al., 2013). The gene discussed is PGR; the disease is triple-negative breast carcinoma.