Pin1 knockdown inhibited proliferation, clonogenicity and tumorigenesis of ESCC. (A) Pin1 was knocked down in CE81T. Downregulation of Pin1 protein and mRNA was confirmed. (B) In MTT assay, cell proliferation was attenuated after Pin1 knockdown. (C) In colony forming assay, the colony number was reduced after Pin1 knockdown. ** and *** denote to p <0.01 and p <0.001, respectively. (D) In xenograft tumor model, tumor size of cells with Pin1 knockdown was smaller than that of parental CE81T cells.