To assess the importance of the PDZ-binding motif for Claudin-2-mediated CRC liver metastasis, we engineered HA-tagged versions of both wild-type Claudin-2 and a mutant lacking the C-terminal PDZ-binding motif in HT-29 CRC cells (Supplementary Fig. 3a)25. The gene discussed is CLDN2; the disease is colorectal carcinoma.