6721
To better understand AhR - driven pathways , we analyzed the transcriptional program in response to coplanar PCB 126 in contact - inhibited rat liver progenitor WB - F344 cells using high - density microarrays .
 Chemical: PCB 126
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: PCB 126