Through the comparison of cytokines and growth factors in the cerebrospinal fluid (CSF) of metastatic medulloblastoma patients with factors also in conditioned media of metastatic MYC amplified medulloblastoma or leptomeningeal cells, we were led to explore the bioactivity of IGF1 in medulloblastoma by elevated CSF levels of IGF1, IGF-sequestering IGFBP3, IGFBP3-cleaving proteases (MMP and tPA), and protease modulators (TIMP1 and PAI-1). This evidence concerns the gene IGFBP3 and medulloblastoma.