GDNF and Alzheimer disease: Of the identified BDE proteins, the increased level in AD were Aβ42, APP, sAPPβ, BACE-1, t-tau, p-T181-tau, p-T231-tau, p-S202-tau, p-S396-tau, p-tau/t-tau, p-T181-tau/t-tau, t-tau/Aβ42, cathepsin D, LAMP-1, GDNF, p-Y-IRS-1, p-S312-IRS-1, p-S312-IRS-1/p-Y-IRS-1, MMP-9, TSPO, ubiquitinylated protein, GFAP, NF-Lch, NS-enolase, and GM1.