Progesterone receptor (PGR) - Marker for female tissues and cancers

The progesterone receptor is a transcription factor that is activated upon the binding of the hormone progesterone, and is important for the establishment and maintenance of pregnancy. The progesterone receptor is expressed by all female tissues (e.g. breast, vagina, uterus and cervix) and clinically; it is used as a marker to diagnose cancers originating from these tissues. Moreover, together with the estrogen receptor, the progesterone receptor is also used as a predictive biomarker since tumors that are estrogen-/progesterone receptor positive are also susceptible to hormone-blocking drugs.