2941
Three experiments using 20 microM 2 - ( hydroxyamino ) - 1 - methyl - 6 - phenylimidazo [ 4 , 5 - b ] pyridine ( N - OH - PhIP ) were performed to induce mutations in the dihydrofolate reductase ( DHFR ) gene of a hemizygous Chinese hamster ovary ( CHO ) cell line ( UA21 ) .
 GENE: dihydrofolate reductase; GENE: DHFR
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 GENE: dihydrofolate reductase; GENE: DHFR