SYP and Parkinson disease: To further identify whether p38 MAPK activation participated in the pathogenesis of PD, primary SNpc neurons were preincubated with p38 MAPK inhibitor SB203580 (24 h, 10 μM) at 8 DIV(days in vitro) and then quantified the synaptic density based on SYP (synaptophysin) at 10 DIV10.