Mitogen-activated protein kinases (MAPKs) mediate signal transduction from cell surface receptors to the nucleus and are classified into various subtypes. p38 MAPK is activated by environmental stresses and inflammatory cytokines and is critical for normal immune and inflammatory responses as it regulates the expression of many cytokines, transcription factors, and cell surface receptors. p38 MAPK activity in heat-shocked HeLa cells and osmotically stressed PC12 cells is inhibited by SB 203580 with an IC50 value of 0.6 μM. SB 203580 also prevents the activation of PKB/Akt by inhibiting phosphoinositide-dependent protein kinase 1 (PDK1) at IC50 values of 3-5 μM. SB 203580 (hydrochloride) has a formulation with greater solubility in organic solvents than standard SB 203580 .
