Polo-like kinase 1 expression is a prognostic factor in human colon cancer

Figure 1 Expression of PLK1 in colon tissue. A: PLK1 expression in epithelium of the basis of normal colon crypts (arrows); B: Weak PLK1 positivity in colon adenoma; C: Weak expression of PLK1 in colon carcinoma; D: Strong positivity for PLK1 in colon carcinoma infiltrating pericolonic soft tissue; E: Transition of slightly dysplastic colon epithelium (small arrows) into colon carcinoma (arrowheads). Note the abrupt onset of PLK1 expression; F : Overexpression of PLK1 in colon carcinoma (arrowheads) infiltrating normal colon mucosa (small arrows). Original magnifications A: ×200, B: ×50, C: ×100, D: ×20, E/F: ×400.