CD24 and periodontitis: The cell model used in this study has been confirmed to show a typical epithelial morphology and high expression of CD24 (a cancer marker) to mimic the important periodontal feature of the epithelial attachment to the tooth and diseased epithelial lining of periodontitis.20, 21 Hence, this cell model can produce consistent and reproducible findings compared to primary epithelial cells, which generally have a very limited lifespan (some only four passages) and are slow to proliferate.