CXCR4 and glioblastoma: In VEGFR-expressing glioblastoma, it has been confirmed that VEGFR inhibitors upregulated CXCR4 through TGF-β/TGF-β receptor [58], and the inhibition of CXCR4 enhanced the efficacy of sunitinib (a multitarget TKI) in preclinical models of human glioblastoma [59].