ERBB3 and medulloblastoma: Similar to discussed in previous sections (i.e., Introduction/gliomas), in other CNS tumors (221–225), as well as medulloblastomas (213, 226–228), as in many other tumors (229), an important driver of proliferative/invasive/aggressive tumor behavior is the presence of EGFR mutations and amplification of various members of the EGFR receptor family (EGFR or ErbB1, HER-2 neu or Erb2, HER-3 or ErbB3, HER-4 or Erb4), particularly EGFR.