BGLAP and osteosarcoma: Furthermore, we analysed the osteoblastic character of OCN+ cells by confocal microscopy and real-time PCR using Saos-2 cells as a positive control, because Saos-2 cells, which are human osteosarcoma cells, exhibit a mature osteoblastic phenotype in humans; are positive for OCN, ALP, and type I collagen; and are commonly used as an osteoblastic model31.