A study by Iglesia et al. using U87 and A172 human glioma cell lines with tumor suppressor gene deletions found that phosphorylated STAT3 molecules transcriptionally repressed IL-8 by occupying its promoter in the nucleus, thereby inhibiting tumor cell proliferation and invasion (de la Iglesia et al., 2008). This evidence concerns the gene CXCL8 and central nervous system cancer.