Caco-2 cells are a cell line derived from human colon adenocarcinoma  with properties similar to intestinal epithelial cells, making them a widely used in vitro model for evaluating oral absorption of new compounds. These cells express the glycoprotein P (P-gp) and BCRP efflux transporters that may play an important role in limiting drug oral absorption.

The bi-directional transport assay with Caco-2 cells is one of the in vitro systems recommended by the Regulatory Agencies to assess the potential of an investigational drug to be a substrate of the P-gp and BCRP efflux transporters. Furthermore, permeability data can aid prioritize compounds during early stages of Drug Discovery and predict qualitatively in vivo oral absorption.