RIPA-56 is a potent (IC50=13 nM, EC50=28 nM for HT-29 cells) and selective inhibitor of Receptor-Interacting Protein 1 (RIP1) kinase with significant metabolic stability (t1/2=128 min human liver microsomal stability assay) 1. RIPA-56 showed excellent kinase selectivity and did not inhibit IDO at 200 µM. It was able to block the progression of multiple sclerosis in an immune-induced demyelination model2.