HDAC9 and neuroblastoma: We chose HDAC8-selective targeting in neuroblastoma for this direct comparison since in our previous studies we observed a particular oncogenic function of HDAC8 in neuroblastoma among all HDAC family members investigated: advanced-stage and metastasized neuroblastoma tumors express high levels of HDAC8.15 Here, we demonstrate the antineuroblastoma efficacy of an HDAC8 inhibitor in vivo at concentrations avoiding unspecific and therapy-limiting side effects.