MYCN and breast cancer: Since TFAP4 has been reported to be a direct transcriptional target of MYC in adult breast cancer cells [6], we investigated whether a similar relationship exists between TFAP4 and MYCN in neuroblastoma by performing expression analysis following knockdown of MYCN in MYCN-amplified neuroblastoma cell lines BE(2)-C, CHP-134 and IMR-32.