SOX2 expression is often seen only in a part of the tumor, and since SOX2 expression is analyzed in just one tissue section per tumor [7], the number of SOX2 positive tumors in our patient cohort may be underestimated and some of the SOX2 negative tumors with down-regulated expression of CDX2 might actually be SOX2 positive. This evidence concerns the gene SOX2 and neoplasm.