Abstract
p27Kip1 (p27) is a member of the cyclin dependent kinase inhibitor (CDKl) family of cell cycle proteins. We analyzed p27 ex-pression in normal endocrine cells, endocrine cell hyperplasia, adenomas and carcinomas. The levels of p27 protein expression decreased during tumor development and progression. This decrease occurs mainly at the post-translational level with protein degradation by the ubiquitin-proteasome pathway. These results indicate that p27 may be a useful immunohistochemical marker to help separate normal from hyper-plastic endocrine cells and adenomas from carcinomas.
