a Cellular activities on Nurr1 and RXRα were determined in uniform Gal4 hybrid reporter gene assays. Data are the mean±S.E.M., n≥3. Remaining activity (rem. act.) refers to 0.1% DMSO treated cells. The selectivity index (SI) was calculated by dividing the EC50 for RXRα activation by the IC50 for Nurr1 inhibition. c Too toxic for characterization at higher concentrations. a Metrics ligand efficiency (LE), lipophilic ligand efficiency (LLE), and size-independent ligand efficiency (SILE) were calculated as described in ref. . b SlogP for LLE was calculated with RDkit.