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We report here on the identification of a 17 kDa variant of the 14 kDa Id-3 protein termed Id-3L (long version) which possesses a unique 60 amino acid carboxy-terminus generated by read through of a ' coding intron ' and alternative splicing .
 60 amino acid carboxy-terminus, Id-3, Id-3L, coding intron, 14 kDa Id-3, 17 kDa variant
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:
 60 amino acid carboxy-terminus, Id-3, Id-3L, coding intron, 14 kDa Id-3, 17 kDa variant