β2-adrenergic receptor-induced p38 MAPK activation is mediated by protein kinase A rather than by Gi or Gβγ in adult mouse cardiomyocytes - Ming Zheng; Sheng-Jun Zhang; Wei-Zhong Zhu; Bruce Ziman; Brian K. Kobilka; Rui-Ping Xiao (Journal of Biological Chemistry, 2000)