F10 and glioblastoma: We further examined if treatment of LN18 GBM cells with PAR activating peptides (AP) specific for each subtype (AP1, AP2, AP3 and AP4) as well as of thrombin (PAR1, 3 and 4 agonist, 30 U/ml) and Factor Xa (PAR1 and 2 agonist, 30 nM) modulates viability of adherent or neurospheric LN18 cells (Figures 4C, D).