DIFFERENTIAL EXPRESSION OF RB2 P130 AND P107 IN NORMAL HUMAN TISSUES AND IN PRIMARY LUNG-CANCER/

Two proteins, p107 and pRb2/p130, which are structurally and functiona lly similar to the product of the retinoblastoma gene (pRb), were clon ed by taking advantage of their ability to bind transforming proteins of DNA tumor viruses through a particular region called the ''pocket d omain.'' Like pRb, both proteins play a fundamental role in growth con trol, Using immunocytochemical techniques, we examined a variety of no rmal human tissues for the expression of pRb2/p130 and p107, Both prot eins were expressed ubiquitously, although a different tissue distribu tion and/or level of expression were found in various organs, Terminal ly differentiated cells, such as neurons and skeletal muscle, showed h igh expression levels for Rb2/p130, whereas p107 was expressed at high er levels in other cell types such as epithelia of the breast and pros tate, We then examined the expression pattern of Rb2/p130 in 158 speci mens of human lung cancer and found an inverse correlation between the histological grading of the tumors, the development of metastasis, an d the level of expression of Rb2/p130.