6611
We developed retroviral vectors in which the constitutive viral enhancer in the U3 region of the 3' LTR is replaced by an autoregulatory enhancer of the erythroid-specific GATA-1 transcription factor gene .
 ( DNA: 3#$%# LTR, None) , ( DNA: erythroid-specific GATA-1 transcription factor gene, None) , ( DNA: U3 region, None) , ( DNA: autoregulatory enhancer, None) , ( protein: transcription factor, None) , ( DNA: constitutive viral enhancer, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( DNA: 3#$%# LTR, None) , ( DNA: erythroid-specific GATA-1 transcription factor gene, None) , ( DNA: U3 region, None) , ( DNA: autoregulatory enhancer, None) , ( protein: transcription factor, None) , ( DNA: constitutive viral enhancer, None) 