NPAT (nuclear protein, coactivator of histone transcription) is a critical transcription regulator essential for cell cycle progression through G1 and S phases 1. The protein serves as a key coactivator of histone gene transcription, working in conjunction with other factors to activate expression of histones H2A, H2B, H3, and H4 genes 1. NPAT functions through CDK2-dependent phosphorylation and localizes to specialized nuclear structures called histone locus bodies (HLBs), where it forms complexes with FLASH and YARP proteins to control histone gene expression during cell cycle progression 12. In human embryonic stem cells, NPAT works with cyclin D2 to maintain self-renewal capacity through regulation of histone biosynthesis 3. Disease relevance includes its role in cancer predisposition, with germline loss-of-function variants identified in hereditary colorectal cancer families, suggesting NPAT functions as a tumor suppressor 4. Additionally, the XPO7-NPAT pathway represents a critical vulnerability in TP53-mutated acute myeloid leukemia, where NPAT retention in the nucleus drives leukemia proliferation 5. NPAT has also been identified as a potential DNA methylation biomarker associated with myopia risk 6. The gene is located on chromosome 11 upstream of ATM and spans at least 44 kb with 18 exons 7.