A potent, cell-permeable inhibitor of MK2 (IC50 = 8.5 nM); less potently blocks MK3 and MK5 (IC50s = 210 and 81 nM, respectively) and is weak or inactive against several other kinases, including other p38 MAP kinase targets; prevents LPS-induced synthesis of TNF-α in human monocyte-like U937 cells (IC50 = 4.4 µM).