Figure 6

Comparison of β-catenin and MTAP immunostaining in normal colonic epithelium (a) and colon carcinoma (b). (a) (I) There was a strong membranous staining of β-catenin detectable in the epithelial cells at the basement and cervix of colonic mucosal crypts (× 100). (II) At the mucosal surface the epithelial cells showed an increasing cytoplasmatic/nuclear staining of β-catenin (× 400). In contrast, CEC at the cryptal basement and cervix were immunohistochemical negative for MTAP (III, × 100) and showed a strong cytoplasmatic immunoreactivity at the cryptal surface (IV, × 400). (b) (I) Colon carcinoma with focal cytoplasmatic and regional nuclear immunohistochemical staining of β-catenin (× 100). (II) Carcinoma segments with predominantly cytoplasmatic β-catenin staining (× 400) showed simultaneously a weak cytoplasmatic MTAP expression (III, × 400). In contrast to sections of colon carcinoma with strong nuclear immunostaining of β-catenin (IV, × 400), a concurrent increasing cytoplasmatic staining of MTAP was detectable (V, × 400).