ERK inhibitor is a cell-permeable inhibitor that binds ERK2 near its docking domain (KD = 5 μM). This prevents its interaction with protein substrates without inhibiting catalytic activity. ERK inhibitor blocks ERK-specific phosphorylation of ribosomal S6 kinase-1 and ternary complex factor Elk-1 but does not affect ERK1/2 phosphorylation by MEK1/2. Presumably through its effects on ERK, ERK inhibitor completely prevents proliferation of HeLa cells (IC50 = 15-20 μM), A549 lung carcinoma cells (IC50 = 25 μM), Sum-159 estrogen receptor-negative breast cancer cells and HT1080 fibrosarcoma cells.
