Abstract: The invention provides a method of a method of characterizing the proliferative state of cells in a biological sample based on detecting transcription factor-mediated phosphorylation of histone H2B (H2B) at residue 36 (numbered according to human H2B). This method optionally includes detection of transcription factor-mediated acetylation of histone H3 (H3) at residue 14 and/or acetylation of histone H4, which also provides an indication of cell proliferation. The invention also provides antibodies specific for H2B phosphorylated at H2B; transcription factor and H2B derivatives and related polynucleotides, vectors, host cells, recombinant production methods and compositions; and screening methods for modulators of H2B phosphorylation at residue 36.