Compared to naïve controls that also received the injections of L-DOPA (20 mg/kg) and benserazide-HCl (12 mg/kg) 2 h before sacrifice, we found a marked increase in the densities of c-Fos-positive (c-Fos+) nuclei in the 6-OHDA-lesioned striatum in both PD and PD-D mice. The gene discussed is FOS; the disease is Parkinson disease.