HOXD8 and squamous cell carcinoma: Further, H3K9me3 (tri-methylation at the 9th lysine residue of Histone H3 protein) marks associated with the heterochromatin state formation were present at higher levels on HOXB7, HOXC10, HOXC13, and HOXD8 in normal oral keratinocytes (OKF6-TERT1R) compared to the tongue derived squamous cell carcinoma-9 (SCC-9) cells43.