GSK484 hydrochloride (GTPL8577) is a selective and reversible peptidylarginine deiminase 4 (PAD4) inhibitor. GSK484 hydrochloride (GTPL8577) demonstrates high affinity binding to PAD4 with IC50s of 50 nM in the absence of Calcium. In the presence of 2 mM Calcium, notably lower potency (250 nM) is observed.