A selective inhibitor of MNK1 in vitro (IC₅₀ = 2.2 μM), with no inhibitory activity against p38, JNK1, ERK1/2, PKC, or Src-like kinases; blocks the phosphorylation of eIF4E in response to TNF-α, arsenite, anisomycin, PMA, or fetal calf serum in 293 cells (IC₅₀ = 3 μM).