p63 is a transcription factor that regulates many cellular activities, including cell proliferation, maintenance, differentiation, adhesion and apoptosis. It has been identified as a sensitive and specific marker for myoepithelial and basal cell populations in prostate, breast, skin and salivary gland. In addition, p63 has shown immunohistochemical utility in the identification of benign and malignant breast lesions. In prostatic carcinomas, it can also be used to detect benign glands alongside malignant glands. p63 can also be used to distinguish adenocarcinomas of the lung, where it is usually negative, from squamous cell carcinomas, which may be useful for advanced stages.