We investigated neuroblastoma and glioblastoma cell lines with mature CIK cells and the PPARγ antagonist GW‐9662 to assess the effects on cell viability, candidate gene expression (Wnt/β‐catenin signalling, DNMT1) and global methylation levels (5‐methylcytosine, LINE‐1). This evidence concerns the gene DNMT1 and neuroblastoma.