Fig 1: Osteoblast Characterization. (A) Human osteoblast (NOB and AIS) cells were cultured in osteogenic medium (ascorbic acid, glycerol phosphate, and dexamethasone) for 28 days. After 28 days, alizarin staining showed reduced mineral deposition in the AIS cells compared to NOB cells (left). Quantification of alizarin red staining (right) measured at an absorbance of 405 nm. *** p < 0.001. (B) Alkaline phosphatase activity detection in osteoblasts derived from the bone of NOB, AIS, and HEK293 cells (negative control) (Scale bar 40 μm). (C) COL1A2 protein expression in NOB and AIS cells. AIS cells had lower levels of COL1A2 compared to NOB cells.