DKK1 and cancer: Intriguingly, the presence of LRP6 does not compete with CKAP4 for binding with DKK1 owing to the different locations of the binding domain; instead, it enhances DKK1-CKAP4 signaling, thereby promoting cancer cell proliferation more than DKK1-CKAP4 interaction alone (Kikuchi et al., 2021).