NF1 and glioblastoma: Thus, we generated SF268 glioblastoma cell lines that stably express, under the control of doxycycline, shRNAs specifically designed to degrade either the GRDI- or GRDII-ΔNLS transcripts or the GRDI- and GRDII-NLS-NF1 transcripts (Scheme 1; for simplicity, we will refer to those as NLS-SF268 cells and ΔNLS-SF268 cells, respectively).