Fig. 8.

Schematic representation of events during MOR gene transcription after stimulation of P19 cells with HDAC inhibitors or retinoic acid-mediated neuronal differentiation. HDAC inhibitor stimulation or neuronal differentiation of P19 cells leads to a general increase in the expression of MSK1 proteins, which are concurrently activated by upstream ERK 1/2 or p38 MAPK. Upon activation, MSK1 increases the activity of transcription factors that bind to the remodeled MOR proximal promoter to increase transcription of MOR gene.