KRT4 and esophageal squamous cell carcinoma: Most of the abnormalities of these proteins occurred at mild and moderate DYS (overexpression of fascin, FADD, CDC25B and underexpression of CK4, annexin I, Fas, caspase 8), which were defined as "early" changes; some occurred at severe DYS and CIS (overexpression of CK14 and FADD), defined as "intermediate" changes; some occurred at the transition from severe DYS and CIS to invasive lesions or at the transition from early stage ESCC to late stage (overexpression of CK14, laminin-5γ2 and SPARC), defined as "late" changes.