['Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is lost as a function of prostate tumor androgen dependence. While the transcriptional activity of the androgen receptor (AR) is inhibited by PTEN in androgen sensitive prostate cancer (CaP), the role of PTEN in androgen disease is unclear.', 'We developed a system where PTEN can be conditionally re-expressed at physiologic levels into a PTEN null metastatic human CaP cell line, C4-2, and androgen responsiveness examined.', 'PTEN induction reduces cell growth and blocks the growth effect of synthetic androgen R1881. The anti-androgen Casodex enhances the growth-inhibitory action of PTEN and this effect is independent of Akt phosphorylation. Combined PTEN induction and Casodex, result in a further decrease in prostate specific antigen promoter activity compared to PTEN but not Casodex alone.'] Does conditional expression of PTEN alter the androgen responsiveness of prostate cancer cells?