PARP1 and neuroblastoma: Among the significantly-higher expressed proteins in the NB AI tumorspheres that we validated using Western blot analysis, was the Poly (ADP-ribose) polymerase 1 (PARP1), melanoma inhibitory activity 3 (MIA3), RhoA and hepatoma derived growth factor-related protein (HDGFR), which are associated with increased metastases, stemness, invasion and malignancy [9, 10, 11, 12].