Figure 4

Immunohistochemical analysis showing loss of PTEN expression in a colorectal adenocarcinoma. A: Colorectal adenocarcinoma showing loss of PTEN expression by immunohistochemistry (×100). The cancer cells show lack of expression, whereas stromal lymphoid and fibroblastic cells demonstrate high levels of PTEN expression in the nucleus with reduced but evident cytoplasmic staining. B: A different region of the same adenocarcinoma magnified (×200) to reveal some foci of entrapped non-cancerous epithelial cells [N.C.] showing PTEN expression in both nuclear and cytoplasmic compartments with weaker expression in their nuclei comparative to the nuclei of lymphoid and stromal cells.