COPB2 (coatomer protein complex I subunit beta 2) is an essential component of the COPI coatomer complex that mediates vesicular transport between the endoplasmic reticulum and Golgi apparatus 1. The protein is critical for embryonic development, as null mutations cause embryonic lethality in mice, while hypomorphic mutations lead to primary microcephaly in humans through increased neuronal apoptosis and reduced cortical layer V neurons 1. COPB2 functions as an oncogene across multiple cancer types, with upregulated expression promoting cell proliferation, invasion, and metastasis while inhibiting apoptosis 2. In colorectal cancer, COPB2 silencing induces apoptosis through JNK/c-Jun signaling pathway activation 3, while in breast cancer it regulates the PI3K/AKT pathway 4. The protein controls cell cycle progression, with silencing causing G0/G1 or S-phase arrest in colon cancer cells 5 and G2-phase arrest in osteosarcoma 6. In hepatocellular carcinoma, COPB2 promotes progression by regulating YAP1 nuclear translocation and affects cisplatin sensitivity 7. High COPB2 expression correlates with poor prognosis in multiple cancers, suggesting its potential as both a biomarker and therapeutic target 86.