ACSL4 and glioblastoma: However, when we knocked down Acsl4 in PG7–Drp1S637A cells, those surrogate markers were once again reversed (Fig. 3H–J, Supplementary Fig. 3A–D), suggesting that dephosphorylation of Drp1 at Ser637 in GBM cells strongly induced Acsl4-dependent ferroptosis.