12016
The low frequency with which these Ig-expressing hybrids are recovered, along with the fact that cell fusions can lead to chromosome loss, led us to propose that this rare phenotype was due to loss of a T-cell-derived chromosome encoding a factor or factors with gene silencing activity .
 ( cell line: Ig-expressing hybrids, None) , ( protein: T-cell-derived chromosome encoding a factor, 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:
 ( cell line: Ig-expressing hybrids, None) , ( protein: T-cell-derived chromosome encoding a factor, None) 