12662
Since one of the two X chromosomes is randomly inactivated at an early stage of female embryonic development , X-linked markers have been used to study the origin and development of various neoplastic disorders in affected heterozygous women ; clonality assays have provided a useful tool to the understanding of the mechanisms underlying the development of neoplasia .
 ( DNA: X chromosomes, None) , ( protein: X-linked markers, 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: X chromosomes, None) , ( protein: X-linked markers, None) 