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). Here, SFRP1 is linked to prostate cancer.