For example, the GTML (Glt1-tTA/TRE-MYCN-Luc) model in which MYCN aberration is driven by the glutamate transporter 1 (Glt1) promoter expressed in hindbrain progenitors develops tumors that closely resemble Group 3, but also shows the features of WNT, SHH, and Group 4 medulloblastoma (24). Here, SHH is linked to medulloblastoma.