In AD individuals, we observed the dysregulation of several mRNA transcripts (AD versus Old: PSME4, POMP, PSMB8, PSMD11, PSMD12, PSMC2; AD versus Young: PSMB8, PSMD12 AND PSMB7) and proteins (AD versus Old: UBB, UBA7, UBE2O, PSMB1, PSMB4, PSMB8, PSMD2, SKP1) related with ubiquitin-proteasome system. This evidence concerns the gene PSMC2 and Alzheimer disease.