6902
These actions are mediated by the activation of estrogen receptors ( ER ) alpha ( ER alpha ) and beta ( ER beta ) , which regulate target gene transcription ( genomic action ) through two independent activation functions ( AF ) - 1 and AF - 2 , but can also elicit rapid membrane initiated steroid signals ( MISS ) .
 Chemical: estrogen; Chemical: steroid
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: estrogen; Chemical: steroid