CD1D and glioblastoma: Next, to assess whether RA-differentiated cells were also sensitive to α-GalCer-dependent iNKT cell-mediated cytotoxicity, we performed an in vitro cytotoxicity assay using RA-differentiated cells from CD1d-positive patient glioblastoma stem-like cells from patient No. 22 or CD1d-negative patient glioblastoma stem-like cells from patient No. 29.