In order to select an etoposide-resistant cell line, HTLA-230, MYCN-amplified human neuroblastoma cells, isolated from a stage IV patient, were treated for 6 months with increasing concentrations of etoposide (1 nM-1.25 μM) and then maintained in culture with the same drug at the concentration of 1.25 μM, which mimics the dose commonly used to treat neuroblastoma patients [18]. Here, MYCN is linked to neuroblastoma.