Besides, compared with the wild type glioblastoma cell line, an increase in PGE2 secretion was observed in TMZ-resistant glioblastoma cell lines (Pt#3-R, P1S, and U87MG-R cells), while a decrease was observed in U87MG-Sp1 cKO cells (Fig. 3c, d). Here, SP1 is linked to glioblastoma.