Characterization by real-time PCR of PC3c cells indicated that ET1 and OPG, two factors that have been implicated in the pathogenesis of osteosclerotic bone metastases from prostate cancer are overexpressed compared to the parental cell line PC3 (Figure 1C-D) while other factors such as fibroblast growth factor 9 (FGF9) and TGFβ are similarly expressed in both cell lines [8,22,23]. This evidence concerns the gene EDN1 and prostate cancer.