WT1 and glioblastoma: GL261 cells, which are murine PD-L1 expressing astrocyte-derived tumor cells commonly used for mouse glioblastoma models, were transduced with mouse WT1 cDNA, and the continued WT1 protein expression of the resultant cells (GL261-WT1) was ensured by Western blotting analysis throughout many cell passages (Figure 1A).