- Reduced glycogen availability is associated with increased AMPKalpha2 activity, nuclear AMPKalpha2 protein abundance, and GLUT4 mRNA expression in contracting human skeletal muscle. Steinberg, G.R., Watt, M.J., McGee, S.L., Chan, S., Hargreaves, M., Febbraio, M.A., Stapleton, D., Kemp, B.E. Applied physiology, nutrition, and metabolism = Physiologie appliquée, nutrition et métabolisme. (2006)