The facts of the matter: What is a hormone?

Thereafter it was only by 1) realizing that the phenotypes of I Esp-/- i and I Osteocalcin-/- i mice were mirror images of each other 2) performing genetic complementation experiments and 3) injecting osteocalcin in wild type mice or treating cells with osteocalcin that the notion that osteocalcin was a hormone was advanced [[6], [50], [53]-[55]]. These studies, through different I in vivo i and I in vitro i assays, all show that osteocalcin, and by that I mean bioactive (undercarboxylated) and not total osteocalcin, has the properties of a hormone. If a hormone is defined by what it does when in excess of baseline in normal animals, then unlike what the Perspective claims from its first to its last paragraph, neither of these papers addresses the question of whether osteocalcin is a hormone. [Extracted from the article]