LZIC (leucine zipper and CTNNBIP1 domain containing) is a conserved vertebrate protein that plays critical roles in cell cycle regulation and neuronal survival. The protein contains both a leucine zipper domain and an ICAT-homologous domain, though unlike ICAT, LZIC does not interact with β-catenin 1. LZIC functions as a key regulator of the G2/M cell cycle checkpoint in response to ionizing radiation (IR), specifically maintaining the late G2/M checkpoint downstream of PIKK signaling 2. Loss of LZIC leads to checkpoint dysregulation, severe aneuploidy, and genomic instability following IR exposure 2. During development, LZIC is essential for neuronal survival, being initially expressed ubiquitously before becoming enriched in the developing brain 1. The gene is located on chromosome 1.32-pter and produces multiple transcript variants 3. Clinically, LZIC expression correlates with cancer prognosis - its downregulation is associated with IR-induced tumor development 2, while upregulation occurs in some gastric cancers 3. Expression analysis shows decreased LZIC levels in aggressive neuroblastomas with 1p deletions 4. These findings suggest LZIC functions as a tumor suppressor through its roles in maintaining genomic stability and proper cell cycle control.