p53 protein expression in squamocellular carcinomas of the lip.

Twenty-six cases of squamocellular carcinomas of the lip were immunostained for p53 protein. Nuclear accumulation of p53 protein was observed in 88% of the 26 carcinomas, in 64% of adjacent "normal" epithelium and in all four cases with adjacent atypical squamous epithelium. 93% of the specimens (13/14) with p53 protein accumulation in "normal" epithelium demonstrated evidence of solar elastosis. UV radiation may induce p53 gene mutation as an early event in the neoplastic transformation.