Histone H3 (di-methyl K14) refers to a specific modification of the histone H3 protein, where the lysine residue at position 14 (K14) is di-methylated. Histones are proteins that package and organize DNA into nucleosomes in the nucleus of cells. They play a crucial role in regulating gene expression by controlling the accessibility of DNA to transcription factors and other regulatory proteins. The methylation of histone lysine residues, including K14, is a post-translational modification that can influence chromatin structure and function. Di-methylation of K14 on histone H3 is associated with specific biological processes and can be used as a marker for certain epigenetic states.