We analysed FBXL4 RNA expression levels by quantitative reverse transcription polymerase chain reaction (q-RT-PCR) in five bone metastases and four primary prostate cancer samples and found a significant reduction in FBXL4 expression in bone metastases and primary cancer samples compared to six benign prostatic hyperplasia (BPH) samples (p = 0.001, Kruskal-Wallis test, Supplementary Figure 1a). This evidence concerns the gene FBXL4 and benign prostatic hyperplasia.