The E2F1 transcription factor plays a crucial role in the control of cell cycle acting as an oncogene,34, 35, 36 so we tested whether its expression is correlated with the expression of PARP1 in 498 primary neuroblastomas (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE62564) and found a positive correlation between the two genes (Figure 4B). Here, E2F1 is linked to neuroblastoma.