PR [SP2]

The human progesterone receptor (PR), is a ligand-activated transcription factor and is a member of the steroid receptor family. PR exists in humans as two isoforms. PR is predominantly expressed in female sex steroid responsive tissues such as the mammary gland, uterus and ovary, but is also found in other tissues such as prostate stromal cells, anterior pituitary gland, and endocrine cells of the Langerhans’ islets.