MAPK1 and schizophrenia: Whilst cortical and/or striatal ERK phosphorylation by aripiprazole and quetiapine integrate multiple signaling pathways to regulate neuronal processes relevant to the symptom domains of schizophrenia, there remains a paucity of data on the effects of these APDs on the expression of downstream proteins such as 90 kDa ribosomal s6 protein kinase (p90RSK) or c-fos, which potentially define their distinct clinical profiles.