CPNE2 encodes a calcium-dependent phospholipid-binding protein involved in calcium-mediated intracellular processes and cell membrane binding. Based on limited published evidence, CPNE2 was identified as a key biomarker associated with neuroblastoma risk and prognosis, showing progressive downregulation with increasing disease risk levels 1. The protein localizes to extracellular exosomes and the plasma membrane, where it mediates calcium-dependent phospholipid interactions and cellular responses to calcium signaling.