While our findings constitute the first report on this interaction for PPOX and FECH in fluorescing and non-fluorescing glioma samples, our results for CPOX are well in accordance with earlier findings by Pustogarov et al. (21) reporting an decrease of CPOX on mRNA level, but increase of CPOX on protein level in fluorescing glioma cell lines. This evidence concerns the gene CPOX and central nervous system cancer.