HDGF and glioblastoma: Other studies have shown the involvement of additional secreted proteins in angiogenesis, such as IL-8 released by glioblastoma cells 112, cysteine-rich angiogenic inducer CYR61 113, 114 and hepatoma-derived growth factor (HDGF) 115 released by bone marrow stem cells and glioblastoma cells, respectively (Figure 3).