- Tissue-specific expression of betaKlotho and fibroblast growth factor (FGF) receptor isoforms determines metabolic activity of FGF19 and FGF21. Kurosu, H., Choi, M., Ogawa, Y., Dickson, A.S., Goetz, R., Eliseenkova, A.V., Mohammadi, M., Rosenblatt, K.P., Kliewer, S.A., Kuro-o, M. J. Biol. Chem. (2007)