These histone proteins are involved in sumoylation, a post-translational modification directed by an enzymatic cascade in which Small Ubiquitin-like Modifier (SUMO) proteins are attached to or detached from other proteins to change their function in cells. Detection of SUMO conjugation or protein Sumoylation can help researchers understand how this modification plays a role in regulating nuclear protein activity and in certain cellular processes, such as transcriptional regulation, apoptosis, nuclear-cytosolic transport, response to stress, protein stability, and progression through the cell cycle.