CDK17 and Alzheimer disease: The findings that MCI brains show increased expression of both PCTAIRE-2 and PCTAIRE-3 and LAD brains show an increase in both PCSTAIRE-2 and PCSTIARE-3 may imply that PCSTAIRE-2 may act early in the development of the disease and persists through the progression while PCTAIRE-3 is associated with the late stage pathological changes in AD.