GAP43 and neuroblastoma: In particular, already within 7 days of cell medium supplementation with all-trans-retinoic acid, neuroblastoma-derived cells show a neuron-like phenotype (Chambaut-Guérin et al., 1995), as confirmed by increased expression levels of the specific differentiation markers GAP-43 (Silvagno et al., 2002), NF-200, and NeuN (Redova et al., 2010).