Figure 4.

Examples of ectopic expression of CA IX and CA XII proteins in various tumors, including regions of necrosis/hypoxia. The glandular cells of the colon are normally CA IX-negative but diffuse immunoreactivity is seen in colon carcinoma (A). The normal glial tissues of the brain show no expression of either CA IX or CA XII protein (B). However, variable degrees of positive staining for CA XII are seen in low-grade glioma (C). In contrast, high levels of CA IX protein expression are observed in glioblastoma multiforme (D) and anaplastic ependymoma (E). Expression of the CA IX protein is seen in necrotic/hypoxic regions of the tumors. This induced expression associated with necrotic/hypoxic regions is also seen in high-grade ductal breast carcinoma (F). The symbol n = area of necrosis. Original magnifications, ×200 (A, D–F) and ×400 (B and C).