SPP1 and glioblastoma: An additional study found that cleaved OPN fragments in CSF were more abundant in glioblastoma patients and, after the analysis of consecutive CSF samples, they identified that these fragment levels were positively correlated with CSF levels of vascular endothelial growth factor (VEGF) (marker of angiogenesis) and TNFα, CCL3 and CCL4 (indicators of inflammation) [106].