PAX-8 is a member of the paired box (PAX) family of transcription factors, which are key regulators in early development. This protein plays a role in development of thyroid follicular cells and the expression of thyroid-specific genes, with mutations in the PAX-8 gene linked to thyroid follicular carcinomas, atypical thyroid adenomas, and thyroid dysgenesis. The PAX-8 protein is expressed in simple ovarian inclusion cysts and non-ciliated mucosal cells of the fallopian tubes, but is absent from normal ovarian surface epithelial cells. PAX-8 is also not expressed in normal lung or lung carcinomas.
