Fig 11.

Schematic depicting the potential roles for claudin-2 in breast cancer liver metastasis. Low levels of claudin-2 expression, and its loss in invasive breast cancers, may be required for local invasion and escape from the primary tumor (model 1). Alternatively, a small percentage of claudin-2-positive cells may persist in invasive cancer cells in the primary tumor (model 2). Elevated expression levels of claudin-2, or selection for preexisting claudin-2-positive breast cancer cells, within liver metastases may serve to enhance the survival of breast cancer cells by promoting interactions between the tumor cell and resident hepatocytes.