19292
The pleiotropic effects of vitamin A are exerted mainly by one active metabolite , all - trans retinoic acid ( atRA ) , which regulates the expression of a battery of target genes through several families of nuclear receptors ( RARs , RXRs and PPAR beta / delta ) , polymorphic retinoic acid ( RA ) response elements and multiple coregulators .
 Chemical: vitamin A; Chemical: all - trans retinoic acid; Chemical: atRA; Chemical: retinoic acid
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: vitamin A; Chemical: all - trans retinoic acid; Chemical: atRA; Chemical: retinoic acid