Our findings raise the possibility that the presence of osteocalcin in the bone micro-environment potentially creates paracrine signaling pathways that might explain the propensity of CRPC to metastasize to bone [53]; and expression of osteocalcin in malignant prostate cell lines and prostate cancer specimens potentially leads to autocrine activation of GPRC6A [54]. Here, GPRC6A is linked to prostate carcinoma.