Role of mitogen- and stress-activated kinases in inflammatory arthritis

Table 1 Specificity and selectivity of inhibitors currently being used to inhibit mitogen- and stress-activated protein kinase 1/2

MSK inhibitors	IC50	Mechanism of action	Ref.
SB747651A	0.5 nmol/L	Selectively targets MSK1/2	[45,100,101]
		Inhibits the N-terminal kinase domain of MSKs
		> 300-fold selectivity over RSK1 and > 3000-fold selectivity over GSK3
Ro-31–8220	8 nmol/L	Inhibitor of PKC, MSK1, RSK, S6K1, GSK3	[85,102]
H89	120 nmol/L	Inhibitor of MSK1, S6K1 and ROCK-II, PKA	[85]

MSK: Mitogen- and stress-activated protein kinase; RSK1: 90 kDa ribosomal S6 kinase (p90rsk), also known as MAPKAP-K1(RPS6KA1); GSK3: Glycogen synthase kinase 3; PKC: Protein kinase C; S6K1: Ribosomal protein S6 kinase beta-1; ROCK-II: Rho-associated protein kinase 2; PKA: Protein kinase A.