TSPAN8 and glioblastoma: The role of tetraspanin 8 in the progression of GBM is suggested by (i) its higher expression in tumor specimen than in nearby normal tissue, (ii) its positive correlation with the degree of histologic malignancy (grading), and (iii) its positive effect on the proliferation and migration of U‐87 MG and U251 MG cells.45, 47