CCTB ileum cells are a cell line derived from the ileum, a part of the small intestine. These cells are used as an in vitro model to study intestinal function, drug absorption, and disease mechanisms affecting the ileum. They are particularly useful for investigating the interactions between the intestinal epithelium and luminal contents., The cells are typically cultured in a specialized medium that supports their differentiation and polarized growth. They express various transporters and enzymes involved in nutrient absorption and drug metabolism. Culture conditions and passage number can affect their functional properties and differentiation state.