TP63 is a nuclear transcription factor and member of the p53 family that is important for development of epithelial tissues. TP63 is a useful marker for distinguishing squamous cell carcinomas of the lung from adenocarcinomas or small cell carcinomas. TP63 is also expressed in basal epithelia (myoepithelial cells) of a number of tissues, including prostate and breast, and is useful for differentiating between benign (presence of myoepithelia) and malignant glands (lacking myoepithelial cells). The marker has high sensitivity and specificity in both primary and metastatic tumors. TP63 antibodies are often used alongside antibodies to NKX2-1 in immunohistochemistry to identify squamous carcinomas of the lung, head and neck as well as ruling out invasion in breast, prostate, and salivary gland cancers. References: Conde, 2010; Rekhtman, 2011; Kalhor, 2006.