MYCN and neuroblastoma: ChIP-chip assays were performed on NB cell lines comprising a MYCN amplified (Kelly), non MYCN amplified (SK-N-AS) and a constitutively over-expressing MYCN cell line SHEP-21N which contains a MYCN trans-gene under the control of a tetracycline responsive repressor element [14] [referred hereafter as SHEP-untreated (high levels of MYCN) and SHEP-treated (low expression of MYCN), as illustrated in Figure S1 C and D].