MYCN and neuroblastoma: The interaction between GRP75 and RARα/RXRα was independently validated in two MYCN-nonamplified (SK-N-SH and SK-N-MC) and three MYCN-amplified NB cell lines (SK-N-DZ, SK-N-BE, and IMR-32) (Figure S3), suggesting a critical role of GRP75 in RA signaling and NB differentiation.