BGLAP and osteoporosis: Previous in vitro studies have suggested that osteocalcin might recruit osteoclast precursors and increase subsequent differentiation of these cells into osteoclasts (Malone et al., 1982; Mundy and Poser, 1983; Chenu et al., 1994), suggesting that osteocalcin might be a novel target for treating osteopenia or osteoporosis.