SMAD4 and adenoma: Among the 18 genes the expression levels of which were significantly different in the early invasive carcinoma group and the flat-type adenoma group, the expression levels of eight genes (p21, MUC-2, Erk1, Mucin 3, αN-catenin, PMS1, Lamin β3, and GAK) and 10 genes (Rho GDIβ, c-jun, Cdc42, iNOS, Galectin-1, TIMP-1, GSTP1, ECGF1, nm23, and Smad4) were significantly higher and lower, respectively, in the flat-type adenoma group than in the early invasive cancer group.