GAP43 and cancer: The depolarization of glioma cell membrane promotes cancer proliferation in xenografts.122 Tumor microtubes driven by growth-associated protein-43 also enhance astrocytoma progression and resistance.120 Approximately, 20% of cancer patients eventually develop brain metastasis, and the incidence of brain metastasis is even higher than that of a primary brain tumor.65,124 Zeng et al.123 have shown that brain metastasis also has a close crosstalk with its microenvironment.