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. © 1996 Wiley‐Liss, Inc.