Broad-spectrum HDAC inhibitors have different effects on the cell cycle of transformed cells, including cell cycle arrests in both G1 and G2/M.32 As transformed cells frequently lack a functional G2 checkpoint, cancer cells arrested in G2/M frequently undergo apoptosis.32 Our observation that HDAC11-depleted neuroblastoma cells accumulate in G2/M, form aberrant spindle assemblies and subsequently undergo apoptosis suggest the effect elicited by pan-HDAC inhibition is at least in part mediated by targeting HDAC11. Here, HDAC9 is linked to neuroblastoma.