How do I test levels of growth hormone signalling? (rapamycin does not interact favorably with GH KO mice)

https://www.pnas.org/doi/10.1073/pnas.1717065115

There are fewer panels for it than even for IGF1

FGF21 inhibits it - Frontiers | FGF21 as Modulator of Metabolism in Health and Disease | Physiology