WT1 and pilocytic astrocytoma: Interestingly, although WT1 is not expressed in astrocytes and is found only in brain endothelium in healthy adult humans (Bourne et al., 2010), its elevated expression is common for brain tumors such as pilocytic astrocytoma (grade I), anaplastic astrocytoma (grade III), and glioblastoma multiforme (grade IV) (Nakahara et al., 2004; Izumoto et al., 2008; Chiba et al., 2010; Rauscher et al., 2014).