6620
One of the best understood apoptotic pathways occurs in T lymphocytes and is mediated by Fas /Fas ligand ( FasL ) interaction .
 Fas, T lymphocytes, FasL, /Fas ligand
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:
 Fas, T lymphocytes, FasL, /Fas ligand