Recent equine-specific immunohistochemical data highlight several promising diagnostic markers: in a pilot equine study, granulosa cells of a GCT demonstrated pronounced membranous staining for moesin and phosphorylated ezrin (p-ezrin), along with a low Ki-67 proliferation index-findings that support the generally benign behavior of these tumors (29, 30). Here, MKI67 is linked to granular cell tumor.