C2CD4A is a nuclear protein with diverse cellular functions, most notably in glucose homeostasis and transcriptional regulation. In pancreatic β cells, C2CD4A functions as a transcriptional coregulator of the glycolytic pathway, regulating glycolytic genes and repressing β cell 'disallowed' genes such as lactate dehydrogenase A 1. The protein is controlled by FoxO1 superenhancers and localizes partially to the plasma membrane under Ca2+ control, with binding partners including secretory-granule-localized PTPRN2/phogrin 2. Genetic variants in the VPS13C-C2CD4A-C2CD4B locus are associated with type 2 diabetes susceptibility across multiple ethnic populations 34. The diabetes risk allele increases C2CD4A expression through enhanced NFAT-mediated islet enhancer activity 4. Beyond metabolic function, C2CD4A plays roles in cancer biology, where it inhibits p53 signaling by promoting p53 ubiquitination and degradation, contributing to colorectal cancer progression 5. The gene is also upregulated in invasive pituitary adenomas and serves as a protective factor against lung cancer in Chinese populations 67. These findings establish C2CD4A as a multifunctional protein involved in metabolic regulation, transcriptional control, and cancer pathogenesis.