Several naphtalene-based inhibitors with submicromolar IC50 have been developed towards the PLPro of the closely-related SARS-CoV virus , and the structure of the inhibitor-bound PLPro has been solved for several of them (termed 15g and 24 in the original studies). Both molecules were shown by these studies to not bind to the active site, but instead to occupy the surface groove responsible for the recognition of the LXGG sequence adjacent to the cleaveable peptide bond . The binding mode of 24 (also called GRL0617) towards PLPro from SARS-CoV2 is identical to that towards SARS-CoV . Besides these molecules, other promising compounds have been identified through large-scale screening , but subsequent assays showed that most of the newly-detected compounds are unfortunately either not selective, cytotoxic or weak binders . Continuing efforts are therefore still needed to find new molecular entities that might be eventually be developed clinical inhibitors of this protein target.