ABSTRACT
P63, a close homolog of the p53 tumor suppressor protein, is associated with keratinocyte cell fate and self renewal of epithelial cells ( 9 , 12 ). The p63 transcription factor is necessary for regenerative proliferation in the development of epithelium ( 13 , 14 ). In the mature epidermis, p63 has two roles: (1) to initiate epithelial stratification during development and (2) to maintain the proliferative potential of basal keratinocytes (14) . Since p63 also counteracts the promotion of differentiation by Notch signaling, a mutual antagonism between p63 and Notch signaling may be an important factor in epidermal homeostasis ( 9 , 11 ).
