So far, HOXD9 is reported to be involved in the regulation of cell proliferation in rheumatoid arthritis[42] and carcinogenesis[43], indicating that HOXD9 may contribute to cell proliferation in HOXD9-expressing cells in gliomas including GCSCs In our preliminary experiment, transiently over-expressed HOXD9 increased the S-phase cell population of U87 cells in cell cycle analysis (data not shown). Here, HOXD9 is linked to central nervous system cancer.