PKA and ERK signaling pathways show cross-talk with PKC and Fyn pathways, respectively, allowing for integration of different effector signals. PKC can be activated by lipid second messengers generated through receptors coupled to phospholipase C and can in turn activate certain adenylyl cyclases (AC2, AC4, and AC7), leading to activation of PKA.66 Since PKA is primarily activated by receptors coupled to AC via Gαs, this PKC–AC interaction allows for integration of intracellular signals arising from PLC- and AC-coupled receptors. Fyn kinase interacts with the 5-HT6 receptor and mediates the serotonin-dependent activation of ERK,263 allowing integration of serotonin signaling with calcium and neurotrophin stimulation of ERK.
