Isoform 1 inhibits p53-dependent transcriptional activation and may function as an oncoprotein. Isoform 2 acts as a negative growth regulator by cooperating with p53 in transcriptional activation of p53-responsive genes and may act as a tumor suppressor. Interacts with H3K4me3 and to a lesser extent with H3K4me2. Isoform 2 interacts with RSL1D1. In the adult, widely expressed with highest levels in thymus and testis. Expressed throughout the whole embryo at all stages of development examined. At day 10, highest expression is found in the yolk sac while at day 16 and 18, higher levels are found in inner compartments of bone. In the embryo, highest expression of isoform 1 is found at day 11 while highest expression of isoform 2 is found at day 7. The PHD-type zinc finger mediates the binding to H3K4me3. The polybasic region (PBR) is responsive to the binding to phosphoinositides (PtdInsPs), including phosphatidylinositol 5-phosphate (PtdIns(5)P). Belongs to the ING family.