3961
The primary and recurrent tumors in Group A did not show structural alterations in the p16 , p15 or CDK4 genes , whereas homozygous codeletion of p16 and p15 was observed in both primary and recurrent tumors in Group B.
 ( DNA: p15, None) , ( DNA: p16, 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: p15, None) , ( DNA: p16, None) 