Figure 1

Pathology criteria for SmoA1 tumor phenotype scoring. Sagittal sections were cut at multiple levels from each cerebellum analyzed at the two-month time point and scored for the presence or absence of tumor formation. Sections displayed in the panels have been stained with a monoclonal cyclinD1 antibody to distinguish tumors (brown stain) from remaining normal cerebellum (blue Haematoxylin counter stain). Additionally, tumors were scored as being non-invasive with no effacement, invasive with minimal effacement or effaced according the criteria displayed in the panels above. Tumor pathology was graded by severity into one of the following three groups: (1) Non-invasive with no effacement: tumors reside on the superficial surface of the molecular layer with a clearly established boundary between the IGL and the tumor. Tumor margins are smooth and the IGL structure remains intact; (2) Invasive with minimal effacement: irregularly-shaped tumor margins with tumor invasion into the deeper region of the molecular layer. The IGL structure remains intact; and (3) Effacement: a significant portion of the cerebellum is encompassed in large dense sheets of tumor cells. Multi-focal tumor formation with irregular tumor margins, invasion into the deeper region of the molecular layer, and disruption of IGL structure are commonly noted.