BCL9 and cancer: The PPI between β-catenin and its cofactor B-cell lymphoma 9 (BCL9) is part of the Wnt signalling pathway which plays a key role in cell proliferation with activation of this pathway found in different cancers.101,102 From the crystal structure, a 35-mer linear peptide (residues 347–381 (53)) from BCL9 was shown to bind β-catenin with a KD of 616 nM in an FP assay.