TGFB1 and glioblastoma: To characterize the cytolytic activity of TGFβ-trapped anti-EGFRvIII CAR T cells against GBM, we created an EGFRvIII-overexpressed cell line from human glioma U87 cells and designated U87-EGFRvIII-luc as the target cells, which constitutively expresses high levels of human EGFRvIII and luciferase (Supplemental Figure 1).