As the presented results are based on just a small number of studies and tumour samples and provide no information about the expression of Sox2 and Sox9 in the tumour surrounding brain tissue19,29,46, we investigated the expression of Sox2 and Sox9 in a large cohort of aCP and pCP using immunohistochemistry (64 aCP, 9 pCP), double-immunofluorescence staining and quantitative PCR (26 aCP, 7 pCP). This evidence concerns the gene SOX2 and neoplasm.