In vitro studies using GBM cell lines have shown that TTFs can increase the plasma membrane's permeability by causing mis‐localisation of specific tight junction proteins (claudin‐5 and ZO‐1).[225] Images of the human GBM cell line U‐87and murine astrocytoma cell line KR158B treated with TTFs for 1 h revealed many perforations scattered throughout the plasma membrane.[226] The results showed that the perforations allowed the uptake of 20 kDa fluorescently labelled dextran particles. The gene discussed is TJP1; the disease is glioblastoma.