4311
Furthermore , immunohistochemical studies demonstrated that VEGFR - 2 ( flk - 1 / KDR ) , expression was elevated significantly in the endothelial cells of microblood vessels after 7 days of E2 exposure .
 Chemical: E2
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: E2