3470
There are two regulatory regions between the US3 and the US6 transcription units .
 GENE: US3; GENE: US6 transcription units
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 GENE: US3; GENE: US6 transcription units