Wnt signal transduction: kinase cogs in a nano-machine?

The control of β-catenin levels is vital to the cell. The primary means of regulation is through ubiquitin-mediated degradation. This process is regulated by Wnt signalling and is frequently disrupted in cancer. Three recent papers show that the initial step in marking β-catenin for degradation involves phosphorylation by casein kinase 1. This then allows phosphorylation by glycogen synthase kinase-3, and the recruitment of ubiquitin-ligase components