GAB1 and medulloblastoma: The WNT-activated medulloblastomas (~ 10% of all medulloblastoma), the two medulloblastoma entities with SHH activation (with or without TP53 alteration, together ~ 30% of all medulloblastomas), and the non-WNT/non-SHH medulloblastomas can be securely differentiated by a set of immunohistochemical markers (Table 2) (Figure 2), namely β-Catenin, Yap1, p75NGFR (or Gab1), and Otx2.