UBE4B and neuroblastoma: In both cell lines and patient tumor samples, decreased UBE4B expression was associated with the highest levels of phosphorylated ERK, while cell lines with increased UBE4B had lower levels of phosphorylated ERK (Figure 7), suggesting an inverse association between UBE4B levels and RAS/MAPK pathway activity and providing a mechanistic link between UBE4B protein expression and neuroblastoma tumor differentiation.