IRF9 and neuroblastoma: First, PTBP2 knockingdown decreased both the mRNA and the protein levels of IRF9, which was rescued by exon 6-7-8 overexpression, while IRF9 (exon 6-7-8)-overexpressing NB cells had higher mRNA and protein levels of IRF9 than the control cells (Fig. S6D and E), indicating that the exon 6-7-8 region plays a key role in IRF9 transcription and translation.