WT1 and neoplasm: However, the increased cellular proliferation rate resulting in the formation of neoplasms with WT1 mutant genotype evident in 5–20% of Wilms' Tumor cases implicates a tumor suppressor role for WT1, indicating both proto-oncogene and tumor suppressor functions for this transcription factor (Algar et al., 1996; Yamagami et al., 1996; Inoue et al., 1998; Menke and Van Der Eb, 1998; Tsuboi et al., 1999; Loeb and Sukumar, 2002; Li et al., 2003; Tatsumi et al., 2008).