Addiction of MYCN amplified cell lines to B-MYB could be explained by two theories: a) B-MYB is required for expression of the MYCN amplicon and addiction of neuroblastoma cells to B-MYB reflects the dependence of amplified cell lines to MYCN expression; b) B-MYB is downstream of MYCN signalling and/or required to overcome senescence/apoptotic signals triggered by MYCN overexpression. The gene discussed is MYCN; the disease is neuroblastoma.