JAK2 and anaplastic astrocytoma: A major focus in glioma has been on aberrant JAK2‐STAT3 pathway activation, which enhances GBM tumorsphere formation and invasiveness in adult malignant glioma grade III (anaplastic astrocytoma), grade IV (glioblastoma), and the most common pediatric brain tumor medulloblastoma [84, 85, 86, 87].