As a logical extension of this pilot study, we report here the measurement of ERK1/2 in CSF samples from 33 patients with Alzheimer dementia (AD), 21 patients with mild cognitive impairment who converted to AD during followup (MCI-AD), 25 patients with stable mild cognitive impairment (stable MCI), and an age-matched reference cohort (n = 16) consisting of nondemented subjects (ND). The gene discussed is MAPK3; the disease is Alzheimer disease.