The H3-3B antibody targets histone H3.3. a variant of the canonical histone H3 involved in epigenetic regulation. Unlike replication-dependent histones, H3.3 is synthesized throughout the cell cycle and incorporated into chromatin independently of DNA replication, primarily at transcriptionally active regions, telomeres, and pericentric heterochromatin. Encoded by the *H3F3B* gene (one of two genes for H3.3. alongside *H3F3A*), this histone variant plays roles in gene expression, genome stability, and cellular differentiation. Mutations in *H3F3B*, particularly at lysine residues (e.g., K27. K36), are linked to cancers such as chondroblastoma and giant cell tumor of bone, where aberrant histone modifications disrupt chromatin remodeling and oncogenic pathways. The H3-3B antibody is widely used in research to study H3.3-specific post-translational modifications (e.g., methylation, acetylation) via techniques like ChIP-seq, immunofluorescence, and Western blot. It helps elucidate mechanisms of epigenetic dysregulation in disease and serves as a tool to explore H3.3's unique roles in development, aging, and cancer progression. Its specificity makes it critical for distinguishing H3.3 from other H3 isoforms in both basic and clinical research contexts.