EXTL3 and glioblastoma: These genes likely function as downstream effectors of STAT3 in GBM to regulate not only cell proliferation (e.g., GAS7, IGFBP2, MEOX2 and MXI1), and but also tumor-stroma interactions by modulating protein secretion (e.g., ANXA1, ARL4C, EMILIN1, EMP2, EXTL3 and PDIA4).