3930
The Id family of helix-loop-helix proteins function as negative regulators of DNA binding, basic helix-loop-helix proteins in the regulation of cell growth and differentiation.
 helix-loop-helix proteins, helix-loop-helix proteins
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:
 helix-loop-helix proteins, helix-loop-helix proteins