Figure 4:

Schematic overview of the cAMP responses induced by EP2 and EP4, adapted from [2]. (A) When only EP4 is active, both ${\mathrm{G}}_{{\alpha }_s}$ and ${\mathrm{G}}_{{\alpha }_i}$ control AC activity. ${\mathrm{G}}_{{\alpha }_s}$ induces a cAMP response that is dampened by ${\mathrm{G}}_{{\alpha }_i}$. The cAMP signal decays over time. (B) When EP2 is activated selectively, only ${\mathrm{G}}_{{\alpha }_s}$ modulates AC activity. The resulting cAMP response does not decay. (C) When both EP2 and EP4 are active, competition for ${\mathrm{G}}_{{\alpha }_s}$ dampens the integrated cAMP response. Signaling crosstalk between EP2 and EP4 allows the cell to respond differently to PGE2 depending on the organization and expression of EP2 and EP4. The drawings in this figure are a simplified representation of the experimental data and are mostly based on the more physiological PGE2 concentrations used (i.e. $0.01-1\mu M$)