SMAD4 and adenoma: Among the 32 genes, the average expression levels of eight genes (Rho GDIβ, c-jun, iNOS, TIMP-1, GSTP1, ECGF1, nm23, and Smad4) and four genes (MUC-2, αN-catenin, PMS1, and GAK) were significantly lower and higher, respectively, in both the flat- and protruded-type adenoma groups than in the early invasive carcinoma group.