DLK1 and glioblastoma: On the contrary, GBM cells also express DLK1 on the membrane, but when cultivated in conditions that promote the maintenance of the stem-like phenotype, they present a more complex DLK1 cleavage.8,11 In fact, when exposed to hypoxic conditions and high HIF levels, DLK1 undergoes an alternative ADAM17-dependent cleavage with the release of an intracellular fragment that then localizes to the nucleus of the GBM cells.