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The mammalian NF-kappaB and octamer binding sites seem to be absent, although there are alternative potential NF-kappaB and octamer-binding elements in the chicken IL2 promoter , in close proximity to their mammalian homologues .
 mammalian NF-kappaB, mammalian homologues, IL2, NF-kappaB, NF-kappaB, octamer-binding elements, chicken IL2 promoter, octamer binding sites
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:
 mammalian NF-kappaB, mammalian homologues, IL2, NF-kappaB, NF-kappaB, octamer-binding elements, chicken IL2 promoter, octamer binding sites