1973
To test the hypothesis that estrogen increases PRL - R expression and sensitivity to prolactin , we next demonstrated that estradiol greatly augments prolactin - induced STAT5 activation .
 Chemical: estrogen; Chemical: estradiol
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
 Entities: estrogen, estradiol 
Answer:
 Chemical: estrogen; Chemical: estradiol