Keratin 8

Keratin, type II cytoskeletal 8 also known as cytokeratin-8 (CK-8) or keratin-8 (K8) is a is_associated_with::keratin is_associated_with::protein that in human is encoded by the KRT8 is_associated_with::gene. It is often paired with is_associated_with::keratin 18.

Utility as an immunohistochemical stain
is_associated_with::Antibodies to CK8 (e.g. CAM 5.2) can be used to differentiate lobular carcinoma of the breast from ductal carcinoma of the is_associated_with::breast. CAM 5.2, an antibody that reacts with an is_associated_with::epitope found on both CK8 and CK18, is used in is_associated_with::immunohistochemistry to demonstrate certain forms of cancer. In normal tissue, it reacts mainly with secretory epithelia, but not with squamous epithelium, such as that found in the skin, cervix, and esophagus. However, it also reacts with a range of malignant cells, including those derived from secretory epithelia, but also some squamous is_associated_with::carcinomata, such as is_associated_with::spindle cell carcinoma. It is considered useful in identifying microscopic metastases of breast carcinoma in lymph nodes, and in distinguishing Paget's disease from is_associated_with::malignant melanoma. It also reacts with is_associated_with::neuroendocrine tumors.

Keratin 8 is often used together with keratin 18 and is_associated_with::keratin 19 to differentiate cells of epithelial origin from hematopoietic cells in tests that enumerate is_associated_with::circulating tumor cells in blood.

Interactions
Keratin 8 has been shown to interact with is_associated_with::MAPK14, is_associated_with::Pinin and PPL.