IPO13 and pterygium: To elucidate the underlying mechanism of increased IPO13 activity in the epithelium of the pterygium, we first determined if IPO13 affects the cell proliferation of cultured PECs by overexpression or silencing of the IPO13 gene, since hyperproliferation of pterygium epithelial cells is considered to partially contribute to the pathogenesis of pterygium [24-26].