I've read this. Nowhere in it did I see any clinical proof that ERβ activation helps. There was a study on genistein(30x affinity for ERβ) that found it inhibited human hair shaft elongation in vivo, leading them to speculate that E2 actually initiates catagen signalling via ERβ rather than the previously believed ERα. The evidence is contradictory and far from conclusive on anything to do with Estrogen. Studies don't only show that estrogen mediates catagen signalling in mice, it has also been demonstrated in human female scalp hair as well. The only question is men. We know there are small differences in follicle hormone signalling between the sexes. For obvious reasons though the use of estrogen hasn't been studied for men. All we have are anecdotal case studies of men growing hair on E2, with the speculation being the MOA is through androgen suppression.