MXI1 and neuroblastoma: Compared with Mxi1-1, Mxi1-0 has an alternative first exon (exon 0), encoding a different SIN3 interaction domain (SID) (Engstrom et al., 2004), and is reported to promote proliferation of various types of cells, such as endothelial cells and neuroblastoma cells (Armstrong et al., 2013; Wu et al., 2017).