Expression of both cell cycle regulators, cdk1 and CCNB1, were analyzed on mRNA and protein level in a panel of NB cell lines presenting either with low MYCN levels (NB69, SK-N-FI, SHEP) or with MYCN amplification/overexpression (IMR-32, NGP, NLF, WAC2). The gene discussed is CCNB1; the disease is neuroblastoma.