NOP16 (NOP16 nucleolar protein) is a nucleolar protein that plays critical roles in ribosomal biogenesis and cellular growth regulation. NOP16 functions as part of a multiprotein complex involved in rRNA production and ribosome assembly, with RNA 3'-phosphate cyclase (RTCD1) as a key interacting partner that synergistically modulates rRNA synthesis and ribosomal biogenesis 1. The protein is directly regulated by the c-Myc transcription factor, which binds to the NOP16 promoter and controls its expression levels 12. In cancer contexts, NOP16 demonstrates significant pathological relevance across multiple tumor types. It promotes hepatocellular carcinoma progression by triggering epithelial-mesenchymal transition (EMT) through the Keap1-Nrf2 signaling pathway 2. In nasopharyngeal carcinoma, NOP16 enhances cell proliferation, migration, and invasion while inhibiting apoptosis via activation of RhoA/PI3K/Akt/c-Myc and IKK/IκB/NF-κB signaling pathways 3. Clinical studies reveal that NOP16 overexpression correlates with poor prognosis in breast cancer patients, particularly when co-upregulated with RTCD1 1. Additionally, loss-of-function mutations in NOP16 are associated with increased susceptibility to neuromyelitis optica spectrum disorder in Chinese populations 4. The protein also serves as a potential biomarker for microvascular invasion in hepatocellular carcinoma and represents a promising therapeutic target for cancer treatment 5.