EDN1 and glioblastoma: In addition, ET1 production in this work was indistinguishably higher in both ECE1cK6R- and ECE1cWT-expressing GBM cells, although the presence of ET1 in their growth media did not alter the capacity of HEY-A8 cells to undergo VM, suggesting that secreted ET1 is not enough to explain the enhanced aggressiveness observed in our GBM cell clones.