Progesterone is an essential regulator of the reproductive events associated with the establishment and maintenance of pregnancy, including ovulation and uterine & mammary gland development. Progesterone exerts its effects via the intracellular progesterone receptor (PR). PR is composed of two isoforms, A and B. The B form of PR acts as a transcriptional activator in different cellular contexts, whereas the A form functions as a strong inhibitor of transcriptional activity. Quantitative detection of PR levels is very important for predicting prognosis and evaluating the outcome of endocrine therapy in patients with breast and/or uterine cancer.


