8995
B lymphocytes from patients with chronic lymphocytic leukemia contain signal transducer and activator of transcription (STAT) 1 and STAT3 constitutively phosphorylated on serine residues .
 signal transducer and activator of transcription (STAT) 1, B lymphocytes, STAT3
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:
 signal transducer and activator of transcription (STAT) 1, B lymphocytes, STAT3