CGP 57380 is a selective inhibitor of MAP kinase-interacting kinase 1 (MNK1) in vitro (IC50 = 2.2 μM), with no inhibitory activity against p38, JNK1, ERK1/2, PKC, or Src-like kinases. It blocks the phosphorylation of eIF4E in response to TNF-α, arsenite, anisomycin, PMA, or fetal calf serum in 293 cells (IC50 = 3 μM). CGP 57380 also dose-dependently inhibits TNF-α production in RAW 264.7 cells that have been co-treated with agonists for Toll-like receptor (TLR)2 (HKLM), TLR4 (LPS), TLR6/2 (FSL), TLR7 (imiquimod), or TLR9 (CpG DNA), presumably by inhibiting MNK1.
