H3S10P is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the phosphorylation the 10th serine residue of the histone H3 protein. The S10 phosphorylation is involved in mitosis, transcription, chromatin condensation, and UVB response. H3S10p causes chromosome condensation and segregation during cell mitosis. H3S10p temporarily increases during mitosis while H3K9me3 decareses and H3K9me3 recovers upon mitotic exit.