6605
This 5 ' splice site sequence was required for enhanced polyadenylation and was recognized by both U1 small nuclear ribonucleoproteins ( snRNPs ) and alternative splicing factor / splicing factor 2 ( ASF / SF2 ) .
 U1 small nuclear ribonucleoproteins, alternative splicing factor, splicing factor 2, ASF, SF2
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 U1 small nuclear ribonucleoproteins, alternative splicing factor, splicing factor 2, ASF, SF2