Higashi et al. investigated the effect of retinoic acid on neuroblastoma cell lines and found that treatment with 1 to 10 μM of 13-cis-retinoic acid for 3 to 12 days upregulated cell expression of chromodomain-helicase DNA-binding protein 5 (CHD5), a tumor-suppressing gene, and induced neuronal differentiation in SH-SY5Y, NGP, and SK-N-DZ cells [226]. This evidence concerns the gene CHD5 and neoplasm.