KLRK1 and glioblastoma: We initially used U87 cells cultured as differentiated GBM cells in normal serum conditions or conditions to promote stem-like features (hereby referred to as U87 GSCs) as a cell line model to investigate NKG2D BiTE activity.25 Assessment of relative surface NKG2DL expression revealed that U87 GSCs had significantly increased NKG2DLs compared with differentiated U87 cells (figure 5A).