2117
Here , we alter the dimerization specificity of Fos by precisely replacing its leucine zipper with that from GCN4 .
 GENE: Fos; GENE: GCN4
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
 Entities: Fos, GCN4 
Answer:
 GENE: Fos; GENE: GCN4