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.
 p15, p16
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 p15, p16