Four NB cell lines, SK-N-AS and SH-SY5Y (MYCN nonamplified), and NB-19 and NGP (MYCN amplified) were cultured in increasing concentrations of Dox alone or in combination with YK-4-279 (1 μM) for 48 h, and then analyzed using the CCK-8 assay. This evidence concerns the gene MYCN and neuroblastoma.