PEDF (encoded by the SERPINF1 gene) was chosen as a key molecule not only because PEDF is significantly differentially expressed between malignant and benign esophageal cells according to mRNA array studies but also because the expression of PEDF in esophageal cancer is different from that in other cancers (Figures S1A, B). Here, SERPINF1 is linked to esophageal cancer.