RUNX3 is a member of the Runt family of transcription factors, playing an important role in the suppression of gastric epithelium cell proliferation, dorsal root ganglia neurogenesis, and T cell differentiation. RUNX3 is also involved in Caspase-3-dependent apoptosis. Protein complexes containing RUNX3 and various transcription factors, such as Smads or β-catenin/TCF4, have tumor suppressor activity and regulate downstream target gene transcription. While typically localized to the nucleus, RUNX3 can be tyrosine phosphorylated and located in the cytoplasm of many cancer cells. This mislocalization of RUNX3 abolishes its tumor suppressor function and contributes to tumorigenesis.
