Histone demethylase that specifically demethylates 'Lys-9' of histone H3, thereby playing a central role in histone code. Demethylation of Lys residue generates formaldehyde and succinate. May have tumor suppressor activity. Its gene is located in the 5q region of the genome which is deleted in del (5q) interstitial deletion, a frequent deletion found in myeloid leukemias and myelodysplasias, suggesting that it may be a good candidate for the del (5q) tumor suppressor gene. A multitude of publications have implicated JMJD1A as a driver of tumorigenesis in a variety of different cancers. Less evidence hints at JMJD1B and JMJD1C as potential oncogenic proteins. And there is persuasive data to suggest that JMJD1B is a tumor suppressor, especially in AML, and JMJD1A and JMJD1C may also be tumor suppressive in germ cell tumors. Tissue specificity: Ubiquitous. Highly expressed in placenta, skeletal muscle, kidney, heart and liver.