Table 3.

Histone 4: PTM quantification as cancer biomarkers.

Modification	Writer	Eraser	Function	Cancer Role	Reference
Histone 4
H4Rme2	PRMT 1	JMJD 6	Facilitates acetylation of H3 and H4 resulting in gene activation	Low levels in breast cancer of poorer prognosis	[31]
	PRMT 5
	PRMT 6
H4K12Ac	Gcn 5		Histone deposition, telomere silencing Transcriptional activation, DNA repair Transcriptional activation	Low levels in breast cancer of poorer prognosis	[31]
	KAT1
	Tip60
	P300
	CBP
	MYST2
H4K16Ac	Gcn 5		DNA damage response & double-strand repair	Loss—Hallmark of cancer Low/absent in majority of breast cancers	[31,54]
	P300	SIRT 1
	CBP	SIRT 2
	hMOF
H4K20Me3	SUV420H1		Gene silencing Indexing of pericentromeric chromatin	Loss—Hallmark of cancer Reduced levels – independently associated with lower disease-free survival in breast cancer High expression (in combination with high H3K9Me3 & low H3K4Me3) correlates to better prognosis in colorectal cancer Significantly lower levels in circulating nucleosomes of colorectal cancer patients	[54,55,56,57]
	SUV420H2
	NSD2