Phosphorylation of ERK1/2 was dramatically reduced or disappeared after treatment with 1 μM U0126 in all cell lines (Fig. 1E); however, as shown in Fig. 1F, ESCC cell lines exhibited resistance to 1 μM U0126, with a half-maximal inhibitory concentration (IC50) ranging from 10 to 30 μM (Fig. 1G). The gene discussed is MAPK3; the disease is esophageal squamous cell carcinoma.