– IU1-47 is a potent, selective small-molecule inhibitor of USP14 with IC50 of 0.6 uM, shows 10-fold more potent over IU1 and retains specificity for USP14; accelerates the rate of degradation of wild-type tau, the pathological tau mutants P301L and P301S, and the A152T tau variant in primary neuronal cultures, a specific residue in tau, lysine 174, is critical for the IU1-47-mediated tau degradation by the proteasome; stimulates autophagic flux in primary neurons.