Figure 1: cAMP dependent pathway: (A) Binding of ligand to GPCR; (B) Activation of GPCR; (C) Activation of Gα stimulatory protein; (D) Activation of enzyme adenylase cyclase; (E) conversion of ATP to cAMP by enzyme adenylase cyclase; (F) Binding of cAMP to PKA leads to its activation; (G) Activated PKA binds to CREB and phosphorylate it; (H) Activated CREB moves in to the nucleus and enhances the gene expression.