Table 4:

Summary of some key ERK models which include cAMP pathways. Main message summarizes the most important findings regarding cAMP activation of ERK. Key components summarize unique aspects of cAMP activation of ERK. Sole cAMP target is PKA unless specified.

Model name	Main message	Key components	PKA targets
Neves et al., 2008 (Hippocampal)	Spatial patterns of activity require feedforward excitation and thin dendritic diameter	cAMP produced by β-AR; No Ras activation of B-Raf	Inhibitory: PTP Excitatory: B-Raf, PDE4
Xu et al., 2010 (PC12 and HEK293)	EGFR and Epac activate ERK while PKA slightly inhibits ERK through inhibition of C-Raf	cAMP input which activates PKA and Epac; Epac activates Rap	Inhibitory: C-Raf
Jain and Bhalla, 2014 (hippocampal)	mRNA synthesis is the result of the synergistic activity of ERK, CaMKIV and mTORC kinases	Adenylyl cyclase, activated by calcium, synthesizes cAMP from ATP	Inhibitory: PP1 (via Inhibitor 1); CaMKIV (via CaMKK) Excitatory: Rap (via Src and RapGAP), mTORC
Gutierrez-Arenas et al., 2014 (Striatum)	STEP activity dictates the dynamics of ERK in response to glutamate and dopamine inputs	cAMP produced by the dopamine D1 receptor; ERK dephosphorylation by STEP, which is regulated by PKA	Inhibitory: STEP, PP1 Excitatory: calcium influx through NMDAR
Khalilimeybodi et al., 2018 (Cardiac cells)	Gi signaling pathway to ERK activation facilitates hypertrophy gene expression through regulation of the hypertrophic factor GATA4	PKA mediated switching of βAR from Gα to Gi, which then recruits ERK through Src	Inhibitory: β2AR Excitatory: ERK (through Gi)
Song et al., 2013 (Striatal neurons)	ERK inhibition of PDE4 during dopamine signaling modulates neuronal excitability by adjusting AMPAR internalization	Positive feedback loop to cAMP mediated by ERK inhibition of PDE4	Inhibitory: PP1 (through I1 and DARPP32) Excitatory: B-Raf, PDE4