CDKN1C encodes the p57Kip2 protein, which functions as a potent cyclin-dependent kinase inhibitor that tightly binds and inhibits several G1 cyclin/CDK complexes, including cyclin E-CDK2, cyclin D2-CDK4, and cyclin A-CDK2 1. The protein serves as a key negative regulator of cellular proliferation and plays a crucial role in maintaining non-proliferative states 12. CDKN1C is located in the imprinted 11p15.5 locus and is expressed only from the maternal allele 1. The gene functions through multiple mechanisms including chr11 looping and SWI/SNF-dependent regulation, and can induce reversible cell dormancy and senescence in cancer cells 34. Loss-of-function mutations cause Beckwith-Wiedemann syndrome with overgrowth, while gain-of-function mutations in the PCNA-binding domain (codons 272-279) result in growth restriction syndromes including IMAGe syndrome 52. The gene shows high placental expression and its dysregulation affects fetal growth 26. CDKN1C expression may serve as a biomarker for lymph node metastasis prediction in papillary thyroid carcinoma 7.