Inhibitor of the regulatory subunit PPP1R15B of protein phosphatase (Kd = 33 nM). Displays >30-fold selectivity for PPP1R15B over PPP1R15A. Inhibits PPP1R15B-mediated dephosphorylation and protein synthesis in vitro. Induces transient reduction in protein synthesis in brains of wild type mice after single dose. Decreases SDS-insoluble huntingtin assemblies and nuclear inclusions in a mouse model of Huntington's disease. Orally bioavailable and brain penetrant. Purity 98%. MW (observed): 231.08