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We also examined mRNA levels of progesterone receptors A and B ( PGR ) , and separately the expression of progesterone receptor B ( PR - B ) .
 Chemical: progesterone; Chemical: progesterone
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: progesterone; Chemical: progesterone