6618
Regulation of Fas ligand expression and cell death by apoptosis-linked gene 4 .
 apoptosis-linked gene 4, 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:
 apoptosis-linked gene 4, Fas ligand