MAPK Cascades in the Brain: Lessons From Learning

The mitogen-activated protein kinase (MAPK) signaling cascades (including the extracellular signal-regulated kinases [ERKs], the c-Jun N-terminal kinases [JNKs], and the p38 stress-activated protein kinases) are abundant in neurons in the mature central nervous system (1 ). Originally, these cascades were discovered as critical regulators of cell division and differentiation in nonneuronal cells, raising the question: What role would these cascades play in nondividing, terminally differentiated neurons in the adult brain?