PYGO2 and neoplasm: Nuclear β-catenin binds to T-cell factor/lymphoid-enhancing factor (TCF/LEF), B-cell lymphoma-9 (Bcl-9) and Pygopus 2 (Pygo2), which initiates transcription of target genes involved in cell growth and proliferation, such as Cyclin D1, C-myc, CyclinA and CD44, which all play important roles in tumorigenesis, tumor progression and prognosis5, 6, 7, 8.