Keratin, type I cytoskeletal 14 (K14)

Keratin, type I cytoskeletal 14 (K14) is an acidic, low molecular weight intermediate filament protein expressed primarily in the basal cells of stratified squamous epithelia, including the epidermis, where it pairs with keratin 5 to form filaments that provide structural integrity, maintain cell shape, and confer resistance to mechanical stress. It serves as a prototypic marker of mitotically active basal keratinocytes, including stem cells and transient amplifying cells, and plays key roles in regulating the balance between cell proliferation and differentiation through interactions with signaling pathways like PI3K/Akt and Hippo/YAP, as well as modulation of Notch1 activation. Knockdown or mutation of K14 impairs proliferation, delays cell cycle progression, promotes differentiation markers such as involucrin and keratin 1, and reduces tumorigenicity in squamous cell carcinoma models. In disease, K14 mutations cause epidermolysis bullosa simplex, a skin blistering disorder, while its expression marks basal-like breast cancers, squamous cell carcinomas, and aids in distinguishing tumor subtypes like basal vs. non-basal breast carcinomas or benign prostate from carcinoma. Although not a primary therapeutic target like receptors or enzymes, K14 is widely used as a diagnostic biomarker in immunohistochemistry for epithelial tumor classification and prognosis.

Other names

Cytokeratin 14CK14Keratin 14KRT14