4617
Two promoters were identified by S1 nuclease mapping : P1 , which lies about 72 bp upstream from the structural gene ; and P2 , which lies about 35 bp upstream .
 S1 nuclease
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 S1 nuclease