SP1 and esophageal squamous cell carcinoma: Because the rs2252070 SNP is located in the Sp1 binding sit of MMP13 promoter, we speculated that this polymorphism will influence gene expression of MMP13. Therefore, we examined the promoter activity of this region by two luciferase reporter constructs (Fig. 2A) with different rs2252070 allele in ESCC KYSE30 and KYSE150 cells.