Inversely correlated expression of p16 and Rb protein in non-small cell lung cancers: an immunohistochemical study.

Cdk4-mediated phosphorylation of Rb protein is inhibited by p16, a product of a possible tumor suppressor gene. We examined the expression of p16 and Rb protein by means of immunohistochemistry in 61 non-small cell lung cancers and have demonstrated an inverse relationship between the expression of p16 and Rb protein: 28/30 specimens that did not stain for p16 stained for Rb and 21/31 p16-positive specimens did not stain for Rb. Only 1 of the p16-negative specimens had a mutation of exon 2 of the CDKN2 gene. Our results indirectly support the theory that p16 expression is negatively regulated by the functional Rb protein.