Abstract: The biological action of progesterone mediates by progesterone receptor（PR） which is expressed as two isoforms，PRA and PRB. PR is a member of ligand-activated nuclear transcription regulators，and it also can active signaling pathways extra-nuclear. PR plays an important role in cell proliferation and differentiation. There are many factors regulating the activation of progesterone receptor，such as synergic regulators，post-translational modifications and gene transcription. The disorder of PR activations may lead to pathologic changes of target organs.

Key words: Receptors, progesterone, Gene expression regulation, Protein biosynthesis, Signal transduction, Transcription