FBXW7 and neoplasm: Immunohistochemical analysis showed that FBXW7, STK40, and PDCD4 protein was moderately/strongly expressed in the basal/suprabasal cells of ZST esophagus, but reduced or absent in hyperplastic/tumor-bearing ZD3T, ZD6T, and ZD12T esophagus (Figure 6B).