JMJD3, also known as KDM6B, is a 1643 amino acid protein, which belongs to the UTX family. JMJD3 is a Histone demethylase that specifically demethylates 'Lys-27' of histone H3, thereby playing a central role in histone code (PubMed:17825402, PubMed:17851529, ). JMJD3 demethylates trimethylated and dimethylated H3 'Lys-27', so it Plays a central role in regulation of posterior development, by regulating HOX gene expression (PubMed:17851529). Histone demethylases are epigenetic actors with a crucial role in cancer by acting as suppressors of tumors or as oncogenes. JMJD3 and UTX (ubiquitously transcribed tetratricopeptide repeat, X chromosome) are transcription activators, being specific H3K27me3 demethylases. JMJD3 is involved in many cellular process such as development, differentiation, senescence and aging by p16, p53 and RB pathways and finally inflammation. Depending on cancer type, JMJD3 expression is increased (prostate and breast cancers, melanoma, gliomas, renal cell carcinoma or decreased (lung, liver, pancreatic, colon and colorectal cancers. This role in carcinogenesis has allowed the development of "epidrugs" to modulate JMJD3 expression (PMID: 29805743 ).