Although the function of the ErbB family on ovarian follicle development, ovulation, and ovarian epithelial tumorigenesis have been extensively studied [20]–[21], [26]–[27], to our knowledge, this is the first direct evidence showing the function of EGF family of ligands, specifically TGFα, on GCT cell growth and possibly in GCT progression. The gene discussed is TGFA; the disease is granular cell tumor.