4304
To elucidate the role of estrogen in the regulation of tumor angiogenesis in the pituitary of female rats , the density of blood vessels was analysed using factor VIII related antigen ( FVIIIRAg ) immunohistochemistry and the expression of vascular endothelial growth factor / vascular permeability factor ( VEGF / VPF ) was examined by Western blot and immunohistochemical analysis .
 Chemical: estrogen; Disease: tumor
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: estrogen; Disease: tumor