To further validate these four model genes, qRT-PCR was performed using surgically resected tumor tissues and normal esophageal tissues, and it was found that the expression of APLP2, CDCA4, and VIM genes was significantly up-regulated in the tumor tissues, whereas the expression of the PTMA gene was also up-regulated but not statistically different (Figures 10A-D). Here, APLP2 is linked to neoplasm.