Contents
	Summary	489
I.	Introduction	489
II.	cAMP in mammalian cells: well‐known second messenger in signal transduction	490
III.	Brief and controversial history of plant cAMP research	490
IV.	TIR1/AFBs‐mediated auxin signaling: canonical transcriptional reprogramming and enigmatic rapid nontranscriptional responses	492
V.	Discovery of the AC activity for TIR1/AFB auxin receptors supports cAMP as the second messenger in canonical auxin signaling	492
VI.	Conclusions	493
	Acknowledgements	494
	References	494