β2-adrenergic cAMP signaling is uncoupled from phosphorylation of cytoplasmic proteins in canine heart - Meike Kuschel; Ying-Ying Zhou; Harold A. Spurgeon; Sabine Bartel; Peter Karczewski; Sheng-Jun Zhang; Ernst-Georg Krause; Edward G. Lakatta; Rui-Ping Xiao (Circulation, 1999)