FLT1 and glioblastoma: Immunolabeling showed the different activation states of HD- and GBM-PLTs, revealing a higher expression of activation markers, pro-angiogenic, and oncopromoter factors, such as P-selectin, VEGFR1, VEGFR2, VWF, S1P, its receptor S1PR1, the kinase SPhK1, and the transporter, SPNS2.