PARP1 and neoplasm: PARP1-dependent gene repression correlates with the presence of the protein on the regulatory regions of the affected genes, as demonstrated by a wide-range analysis of gene expression in MCF7 tumor cells75 and in human embryonic stem cells76 as well as for specific genes such as PARP1 itself in Ewing's sarcoma cells77 and IL6 in the RAW 264.7 macrophage cell line 74.