2308
LIF induced a dose-dependent increase in p24 antigen production in the chronically infected promonocytic cell line U1 .
 chronically infected promonocytic cell line U1, p24 antigen, LIF
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:
 chronically infected promonocytic cell line U1, p24 antigen, LIF