Our results are supported by previous studies that reported that MMP9 binds to TIMP1 while failing to bind MMP2.26 Furthermore, Axl has been reported to regulate MMP2 at the transcriptional level in ovarian cancer through the PI3K pathway.25 We have previously shown Axl to activate the PI3K pathway in glioma and Axl inhibition to suppress it,15 indicating that the same regulation exists in glioma. This evidence concerns the gene MMP9 and central nervous system cancer.