['Overexpression of cyclin D1 has been documented in a number of human cancers. Increased expression of cyclin D1 can contribute to cellular transformation and abnormal proliferation.', 'Quantitative RT-PCR and/or Western blot analysis were used to determine the level of cyclin D1 expression in 96 human prostate tumors, 15 benign prostate hyperplasias, 4 prostate cancer cell lines, and 3 xenografts.', 'Our results demonstrate that 4.2% of the prostate tumors examined overexpressed cyclin D1 transcripts. In the cell lines, expression was normal, with the exception that reduced levels of cyclin D1 transcript and protein were observed in the DU145 cell line, as expected from cells with mutant RB. Normal levels of cyclin D1 were found in all xenograft tumors and BPH specimens examined.'] Is overexpression of cyclin D1 rare in human prostate carcinoma?