5598
The basal promoter strength of constructs that contained deletions in the U5 region of the LTR was analyzed by chloramphenicol acetyltransferase ( CAT ) assays following transfection of HeLa cells or Jurkat T - cells in the presence or absence of viral transactivator tax protein .
 U5 region, chloramphenicol acetyltransferase, CAT, tax
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 U5 region, chloramphenicol acetyltransferase, CAT, tax