3085
In K562 cells , using the bicistronic vector , selection with colchicine led to at least 20 - fold higher expression of the MDR1 gene product than did selection with G418 , suggesting that the stringent MDR1 selection system is very efficient for obtaining overexpression of foreign genes .
 GENE: MDR1 gene product; GENE: MDR1
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: MDR1 gene product; GENE: MDR1