8467
Consistent with this interpretation , a mutant form of XRN1 , which encodes a 5 ' - 3 ' exonuclease , was identified as an extragenic suppressor that increases the half - life of rhis4 mRNA , leading to a 10 - fold increase in steady - state mRNA levels compared to the wild - type HIS4 mRNA level .
 XRN1, rhis4 mRNA, wild - type HIS4 mRNA
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 XRN1, rhis4 mRNA, wild - type HIS4 mRNA