MAPK1 and Parkinson disease: For this purpose, the kinetic changes of the phosphorylated protein (p-CREB, p-AKT, and p-ERK) levels, which regulate the neuronal cell survival, were determined by quantitative ELISA following the treatment of the cellular PD model by LNPs versus 6-OHDA-damaged and RA-only treated cells (referred to as RA/FBS(-) control).