CKAP4 is identified as a receptor for Dickkopf in cancer cells.

The secretory protein Dickkopf-1 (DKK-1) is a known Wnt antagonist and has been shown to suppress tumorigenesis in some cancer cells; however, it is also upregulated in many types of cancer and associated with poor prognosis. Wnt-independent mechanisms by which DKK-1 promotes cancer cell proliferation are not well understood. In this issue of the JCI, Kimura and colleagues demonstrate that DKK-1 interacts with cytoskeleton-associated protein 4 (CKAP4) to promote activation of AKT. They show that both DKK-1 and CKAP4 are frequently upregulated in pancreatic and lung cancers. Importantly, targeting this interaction with an anti-CKAP4 antibody prevented tumor formation in murine xenograft models. These results identify a previously unrecognized DKK-1-mediated pathway and suggest CKAP4 as a potential therapeutic target for certain cancers.