To test the effects of retinoids on human MYCN-amplified neuroblastoma cells, we treated two MYCN gene amplified neuroblastoma cell lines (BE2C and NGP) with all-trans retinoic acid (ATRA), an active metabolite of isotretinoin, for 6 days and then examined its effects on cell growth and viability. This evidence concerns the gene MYCN and neuroblastoma.