CETN1 (centrin 1) is a calcium-binding protein that plays critical roles in centrosome function and spermatogenesis. As a testis-specific retrogene located on chromosome 18, CETN1 is exclusively expressed in adult testis under normal conditions 1. The protein localizes to the post-acrosomal region of sperm heads and contributes to proper sperm morphology maintenance during spermiogenesis 2. CETN1 is essential for normal cell division, as functional variants lead to multipolar cells, fragmented nuclei during mitosis, and impaired ciliary dynamics 3. Beyond reproductive function, CETN1 functions as a cancer testis antigen (CTA), showing aberrant upregulation in various malignancies including prostate, pancreatic, and breast cancers while remaining silenced in normal somatic tissues 45. In cancer contexts, CETN1 promotes cell proliferation, tumor growth, and metastasis, with expression regulated by promoter methylation 45. The protein's cancer-specific expression pattern makes it an attractive target for immunotherapy and biomarker development, particularly for pancreatic adenocarcinoma where radioimmunotherapy approaches show promise 6. CETN1's dual roles in normal spermatogenesis and cancer progression highlight its importance in cell division control and reproductive health.