NME9 is a Group II member of the NME/NM23 family of nucleoside diphosphate kinase (NDPK) proteins 1. Unlike Group I NME proteins (Nme1-4), Group II members including NME9 lack measurable NDPK activity despite possessing NDK domains 1. NME9 likely functions as a regulator of microtubule physiology based on its association with dynein axonemal particles. The evolutionary origin of NME9 dates to duplication events preceding the chordate radiation, separating it functionally and evolutionarily from the catalytically active Group I members 2. While ancestral NME Group II proteins demonstrated DNA-binding capacity and could suppress cell proliferation and anchorage-independent growth, human NME9 appears to have diverged from these functions during eukaryotic evolution 1. The specific tissue expression patterns and molecular functions of NME9 among vertebrates remain incompletely characterized, representing a gap in current knowledge that warrants further investigation 2. NME9's role in disease contexts has not been established in available literature, limiting clinical significance assessment.