CDC23 is a core component of the anaphase promoting complex/cyclosome (APC/C), a cell cycle-regulated E3 ubiquitin ligase essential for controlling progression through mitosis and G1 phase 1. The protein contains 9 tetratricopeptide repeat (TPR) units and is ubiquitously expressed as a 591-amino acid protein 2. CDC23 functions within the APC/C to mediate ubiquitination and degradation of cell cycle regulatory proteins, including cyclin B1 and securin, which is critical for the metaphase-to-anaphase transition 13. The protein is required for proper regulation of CDC20 proteolysis during S phase and early mitosis 4. Functionally, CDC23 localizes to the nucleus and its TPR domain is essential for protein stability and function 5. Mutations in CDC23 cause female infertility characterized by oocyte maturation defects, with homozygous variants leading to decreased protein levels, altered cellular localization, and accumulation of cell cycle substrates 16. CDC23 is also overexpressed in papillary thyroid cancer, where its knockdown inhibits cellular proliferation and causes cell cycle arrest in S and G2/M phases 3. These findings establish CDC23 as a critical regulator of cell cycle progression with implications for both reproductive biology and cancer.