Secreted Frizzled-related protein-1 was reported to inhibit RANKL-dependent osteoclast formation (Hausler et al, 2004) and RANKL is found in prostate cancer cells, where it is thought to mediate the effects of prostate tumour cells on osteoclastogenesis in vivo (Zhang et al, 2001). This evidence concerns the gene SFRP1 and prostate carcinoma.