Intracellular Signalling Through Adenosine Receptor A2b and Adenosine,Protein,Adenosine is thought to play a role in the pathophysiology of asthma. Stimulation of A2B can induce production of interleukin-8 mast cells. The adenosine receptor A2b activates G(s) proteins which lead to the activation of adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (protein kinase A) which phosphorylates down stream effectors that lead to a specific cellular response. This occurs though activation of the MAPK/ERK signaling cascade.