It was shown that CST1 overexpression significantly upregulated not only the phosphorylation of key effectors MEK1/2 and ERK1/2 in MEK/ERK pathway, but also the expression of EMT-related molecular proteins including transcription factor Slug and matrix metalloproteinase MMP2, and inhibit the expression of epithelial marker E-cadherin, thus promoting the migration and invasion ability of ESCC cells. Here, MAPK3 is linked to esophageal squamous cell carcinoma.