1496
LTR -directed transcription was measured by using luciferase reporter constructs that were transiently transfected into cultured cells .
 cultured cells, luciferase reporter constructs, LTR
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 cultured cells, luciferase reporter constructs, LTR