Editing Progesterone (section)

====Ductal development====
Though to a far lesser extent than estrogen, which is the major mediator of mammary ductal development (via the [[estrogen receptor alpha|ERα]]),<ref name="StraussBarbieri2013">{{cite book|vauthors=Barbieri RL|chapter=The Breast|veditors=Strauss JF, Barbieri RL|title=Yen and Jaffe's Reproductive Endocrinology|chapter-url=https://books.google.com/books?id=KZ95AAAAQBAJ&pg=PA236|date=13 September 2013|publisher=Elsevier Health Sciences|isbn=978-1-4557-2758-2|pages=236–|access-date=1 February 2016|archive-date=14 January 2023|archive-url=https://web.archive.org/web/20230114025044/https://books.google.com/books?id=KZ95AAAAQBAJ&pg=PA236|url-status=live}}</ref><ref name="pmid24718936">{{cite journal | vauthors = Scaling AL, Prossnitz ER, Hathaway HJ | title = GPER mediates estrogen-induced signaling and proliferation in human breast epithelial cells and normal and malignant breast | journal = Hormones & Cancer | volume = 5 | issue = 3 | pages = 146–160 | date = June 2014 | pmid = 24718936 | pmc = 4091989 | doi = 10.1007/s12672-014-0174-1 }}</ref> progesterone may be involved in ductal development of the mammary glands to some extent as well.<ref name="pmid23705924">{{cite journal | vauthors = Aupperlee MD, Leipprandt JR, Bennett JM, Schwartz RC, Haslam SZ | title = Amphiregulin mediates progesterone-induced mammary ductal development during puberty | journal = Breast Cancer Research | volume = 15 | issue = 3 | pages = R44 | date = May 2013 | pmid = 23705924 | pmc = 3738150 | doi = 10.1186/bcr3431 | doi-access = free }}</ref> PR knockout mice or mice treated with the [[antiprogestogen|PR antagonist]] [[mifepristone]] show delayed although otherwise normal mammary ductal development at puberty.<ref name="pmid23705924" /> In addition, mice modified to have [[overexpression]] of [[progesterone receptor A|PRA]] display ductal hyperplasia,<ref name="pmid26266959" /> and progesterone induces ductal growth in the mouse mammary gland.<ref name="pmid23705924" /> Progesterone mediates ductal development mainly via induction of the [[gene expression|expression]] of [[amphiregulin]], the same [[growth factor]] that estrogen primarily induces the expression of to mediate ductal development.<ref name="pmid23705924" /> These animal findings suggest that, while not essential for full mammary ductal development, progesterone seems to play a potentiating or accelerating role in estrogen-mediated mammary ductal development.<ref name="pmid23705924" />