This may be particularly beneficial for drugs in clinical trials for the treatment of neuroblastoma such as irinotecan and topotecan and, as suitable cohorts emerge, this possibility should be explored by examining the relationship between clinical outcome and MRP4 expression in primary tumors of neuroblastoma patients receiving these drugs (Kushner et al., 2006; Simon et al., 2007). Here, ABCC4 is linked to neuroblastoma.