Our previous Affymetrix microarray data show that the HDAC inhibitor Trichostatin A up-regulates TP53INP1 gene expression, and the current study reveals that treatment of neuroblastoma cells with JQ1 or I-BET151 considerably reduces N-Myc expression and up-regulates TP53INP1 expression, and that a low level of TP53INP1 expression in human neuroblastoma tissues correlates with a high level of N-Myc expression and poor prognosis. This evidence concerns the gene HDAC9 and neuroblastoma.