MYCN and neuroblastoma: Expression of mRNAs in 24 neuroblastoma cell lines and 40 tumor samples using RT-PCR suggests that expression of c-Kit, PDGFR-β, and Flt-3 mRNA is associated with neuroblastoma in patients under 1 year, while the loss of expression of these kinases is associated with N-Myc amplification in patients over 1 year of age with advanced stage of neuroblastoma [21].