PTHLH and posterior cortical atrophy: We hypothesize that this discrepancy is attributed to PSA, which can cleave PTHrP at the position of its 23rd amino acid; the degraded and deactivated PTHrP fails to bind with PTH/PTHrP receptors on OB/OC surfaces, resulting in decreased osteolytic effects of PTHrP and relatively enhanced osteogenic processes at PCa metastatic sites (50, 56).