Concomitant Presence of p16/Cyclin‐dependent Kinase 4 and Cyclin D/Cyclin‐dependent Kinase 4 omplexes in LNCaP Prostatic Cancer Cell Line

The cyclin D/cyclin‐dependent kinase (CDK)/CDK‐inhihitory proteins/retinoblastoma protein (pRb) pathway is hypothesized to control the G1‐S check point. The role of this pathway is reported to be different depending on the status of pRb. In the present study, we examined nine human urological tumor cell lines. Cells lacking functional pRb expressed p16, instead of forming cyclin D/ CDK4 complex. In the LNCaP prostatic cancer cell line, however, both p16/CDK4 and cyclin D/ CDK4 complexes were present independently, probably because of partial loss of pRb. In view of the concomitant presence of the incompatible complexes, LNCaP should provide us with a valuable model for the study of this pathway in cancer cells.