 Because this pocket is distinct from the ARM domain's "main" binding site, there is no competition between alpha-catenin and E-cadherin or between TCF1 and BCL9, respectively.On the other hand, BCL9 and BCL9L must compete with α-catenin to access β-catenin molecules.The cellular level of beta-catenin is mostly controlled by its ubiquitination and proteosomal degradation.