28071
In in vitro end - joining systems based on human cell extracts , addition of Artemis , but not Metnase , effected robust trimming of an unligatable 3 ' - PG overhang , resulting in a dramatic stimulation of ligase IV - and XLF - dependent end joining .
 Chemical: 3 ' - PG
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: 3 ' - PG