In line with this, 5-HT4R activation by RS-67333, ML-10302, or SSP-002392 attenuated Aβ pathology, neuroinflammation, and neuronal loss in multiple transgenic AD mouse models.310, 311, 312, 313, 314, 315 Mechanistically, Aβ reduction in the ISF may be explained by PKA-mediated activation of the mitogen-activated protein kinase kinase (MEK)/ERK cascade. The gene discussed is HTR4; the disease is Alzheimer disease.