Effect of MEK inhibition on neurite outgrowth and transcriptional responses stimulated by NGF. A, This schematic diagram depicts a scenario in which Egr induction is located downstream of MEK activation by NGF. In this model, UO126, an MEK inhibitor, and the Egr inhibitor construct Δ(1-249)Egr3 block at sequential steps in the signaling pathway linking NGF receptor activation to neurite outgrowth. B, The bar graph presents the effect of pretreating cells with UO126 (15 μm) on neurite outgrowth induced by NGF.C, The bar graph shows the effect of UO126 (15 μm) on the ability of NGF to stimulate ERE-mediated and Elk1-mediated transcription.