Based on limited published evidence, SLX9 is a ribosome biogenesis factor localized to the nucleolus that mediates protein-protein interactions. SLX9 functions as a nuclear export factor for pre-40S ribosomal subunits, associating with maturing pre-40S complexes in the nucleoplasm to confer export competence prior to cytoplasmic release 1. The protein operates within the coordinated assembly pathway following dissociation of 90S precursor factors and repositioning of other assembly factors like RRP12 and TSR1.