Although we covered three different promoter regions between -445 up to +370 relative to TSS, we failed to determine a correlation between ATRA sensitivity and CRABP2 promoter methylation as it was shown for other cancer cells such as for gliomas, medulloblastomas, Wilms tumors and pancreatic adenocarcinomas [56, 61–63]. The gene discussed is CRABP2; the disease is central nervous system cancer.