Interestingly, after administration of dopamine precursor 3,4-dihydroxyphenyl-L-alanine (L-DOPA), the expression of GADD45β in the dorsal striatum of 6-OHDA-induced PD mice was dramatically higher than that of the control group mice; the level of GADD45β was positively correlated with the dose of L-DOPA. The gene discussed is GADD45B; the disease is Parkinson disease.