GDF2 and glioblastoma: Novel ligand‐receptor pairs like GDF2‐(ACVRL1 + BMPR2) (Figure 6A), GRN‐SORT1 (Figure 6B), TNFSF12‐TNFRSF12A (Figure 6C), EPO‐EPOR (Figure 6D), CGA‐FSHR (Figure 6E), and NAMPT‐(ITGA5 + ITGB1) (Figure 6F) was first identified between GBM cells and immunocytes.