TP53 and neuroblastoma: This is consistent with studies which have shown a decrease in p53 expression following retinoic acid induced in vitro differentiation of neuroblastoma cell lines (Sidell and Koeffler, 1988; Davidoff et al., 1992; Chen et al., 2007), and also during neuronal development/differentiation (Eizenberg et al., 1996; Ferreira and Kosik, 1996).