TBRG1 (transforming growth factor beta regulator 1), also known as NIAM (nuclear interactor of ARF and MDM2), functions as a growth inhibitor and tumor suppressor that maintains chr11 stability 1. The protein acts through multiple mechanisms to activate p53, including disrupting p53-MDM2 interactions, inhibiting p53 polyubiquitination, and promoting p53 K120 acetylation through association with Tip60 2. TBRG1 contains a novel FYR domain with an alpha+beta fold structure that may be important for its chr11-associated functions 3. The protein causes G1 cell cycle arrest and collaborates with CDKN2A to restrict proliferation, though it can inhibit DNA synthesis independently of both ARF and p53 1. TBRG1 deficiency in mice results in chr11 instability and predisposition to proliferative lesions including B-cell lymphomas, with 50% of aged TBRG1-deficient mice developing tumors 4. Clinically, reduced TBRG1 expression has been observed in primary human tumors and is associated with poor prognosis in high-grade serous ovarian cancer 15. The gene has also been implicated as a candidate in autosomal recessive intellectual disability disorders 6.