Furthermore, levels of FKBP51 are elevated in the AD brain,30, 31, 33 FKBP51 co-localizes with tau,25 and endogenous tau levels are reduced in double knockout mice for FKBP51.30, 31 Furthermore, we recently showed that LA101 reduces the affinity of FKBP51 for Hsp90, which could limit access of tau to FKBP51 activity. This evidence concerns the gene FKBP4 and Alzheimer disease.