6620
We report the molecular cloning and functional characterization of USF2 isoforms , corresponding to a 44 - kDa subunit , USF2a , and a new 38 - kDa subunit , USF2b , generated by differential splicing .
 USF2 isoforms, USF2a, USF2b
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 USF2 isoforms, USF2a, USF2b