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These studies suggest that the divergent X2-box of the class II major histocompatibility complex promoters plays an important role in influencing differential expression of the human class II isotypes .
 human class II isotypes, class II major histocompatibility complex promoters, divergent X2-box, class II major histocompatibility complex
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:
 human class II isotypes, class II major histocompatibility complex promoters, divergent X2-box, class II major histocompatibility complex