Because expression of mdr-1 is increased in neuroblastoma cell lines by differentiating agents, the authors hypothesized a similar correlation with differentiation in vivo in neuroblastomas.
Expression of N-myc, c-myc, and MDR-1 proteins in newly established neuroblastoma cell lines: a study by immunofluorescence staining and flow cytometry.
Many of the neuroblastoma samples were also evaluated for N-myc amplification but there was no correlation between N-myc copy number and the level of MDR1 mRNA expression.
Decreased expression of the N-myc oncogene in neuroblastoma cell lines SH-SY5Y and BE(2)-C, following treatment with retinoic acid, was paralleled by down-regulation of MRP gene expression, contrasting with increased expression of the MDR1 gene.