Purity >98%. GSK481 is an inhibitor of receptor-interacting serine/threonine protein kinase 1 (RIP1 or RIPK1) that blocks autophosphorylation of Ser166 on wild-type human RIP1 with an IC50 value of 2.8 nM. It is selective for RIP1 over a panel of over 450 other kinases, including RIP3. GSK481 inhibits RIP1 from human and cynomolgus monkey but is at least 100-fold less potent against non-primate RIP1.