The function of PGR (progesterone receptor, Ensembl gene identifier ENSG00000082175) is as follows. The steroid hormones and their receptors are involved in the regulation of eukaryotic gene expression and affect cellular proliferation and differentiation in target tissues. Depending on the isoform, progesterone receptor functions as a transcriptional activator or repressor. {ECO:0000269|PubMed:10757795, ECO:0000269|PubMed:1587864, ECO:0000269|PubMed:37478846, ECO:0000269|PubMed:9407067, ECO:0000305}. [Isoform A]: Ligand-dependent transdominant repressor of steroid hormone receptor transcriptional activity including repression of its isoform B, MR and ER. Transrepressional activity may involve recruitment of corepressor NCOR2. {ECO:0000269|PubMed:7969170, ECO:0000269|PubMed:8180103, ECO:0000269|PubMed:8264658, ECO:0000305, ECO:0000305|PubMed:10757795}. [Isoform B]: Transcriptional activator of several progesteron-dependent promoters in a variety of cell types. Involved in activation of SRC-dependent MAPK signaling on hormone stimulation. . [Isoform 4]: Increases mitochondrial membrane potential and cellular respiration upon stimulation by progesterone.