6041
We have explored the mechanism of action of the fibronectin splicing enhancer and found that the SE element is required for efficient assembly of early splicing complexes , allowing a more efficient interaction of the U2 snRNP with branch site sequences .
 fibronectin splicing enhancer, U2 snRNP
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 fibronectin splicing enhancer, U2 snRNP