The Phospho-B23 (Thr199) antibody detects the phosphorylated form of nucleophosmin (B23/NPM1) at threonine 199. a post-translational modification critical for regulating B23's cellular functions. B23 is a multifunctional nucleolar protein involved in ribosome biogenesis, chromatin remodeling, and cell cycle control. Phosphorylation at Thr199. mediated by cyclin-dependent kinases (CDKs) during mitosis, promotes B23's dissociation from nucleoli and redistribution to the nucleoplasm or cytoplasm, facilitating processes like centrosome duplication and mitotic progression. This modification is also linked to cellular stress responses, DNA damage repair, and apoptosis. Dysregulation of B23 phosphorylation is implicated in cancer, where overexpression or mutations in B23 are common. The Phospho-B23 (Thr199) antibody is widely used in research to study cell cycle dynamics, nucleolar stress, and cancer biology through techniques like Western blotting, immunofluorescence, and immunohistochemistry. It helps elucidate B23's role in tumorigenesis, particularly in hematologic malignancies and solid tumors, as well as its interaction with tumor suppressors like p53. Researchers also utilize this antibody to explore B23's involvement in neurodegenerative diseases and viral infections, where nucleolar disruption occurs. Specificity for the phosphorylated epitope ensures accurate detection of the active/modified form, making it a key tool for understanding B23's phosphorylation-dependent mechanisms in health and disease.