HOXA9 and neoplasm: A molecular consequence of these changes was shown to be reduced TET1 binding to one of its known target genes, the HOXA9 tumour suppressor gene which codes for a transcription factor that is a positive regulator of cell fate determination and terminal differentiation, suggesting the possibility that poly(ADP-ribosyl)ation, through TET1 activity could control a network of genes due to its ability to affect both DNA and H3K4 methylation on specific genes.