FLT1 and anaplastic astrocytoma: Chan et al. [25] have demonstrated that overexpression of both VEGFR1 and VEGFR2 was found in the tumor vasculature of grade IV glioma; whereas a weak or no expression of VEGFRs was found in the astrocytomas of grade II, anaplastic astrocytomas, and oligodendroglioma tumors.