PTHrP, SOX9, and the reason why estrogen actually closes growth plates.
As most people know, higher estrogen levels will lead to faster closure of the growth plates. However, estrogen cannot solely drive closure. Without it, as seen in aromatase-deficient individuals, plates fail to fuse entirely and growth continues into adulthood. So why is this the case? I'm going to explain PTHrP, SOX9, and the link to estrogen. This is more of an introduction to the actual biolog…