16073
Histology was conducted on 2 cardiac proteins critical to embryonic heart development , ventricular myosin heavy chain and titin , to investigate potential mechanistic effects of PCBs on heart development , but no difference was observed in spatiotemporal expression .
 Chemical: PCBs
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: PCBs