4489
Whereas 94-kD STAT5A was clearly tyrosine phosphorylated and bound to the enhancer element , the gamma response region ( GRR ), of the Fc gamma RI gene , substantially less tyrosine phosphorylated STAT5B bound to the immobilized GRR element .
 STAT5B, GRR element, enhancer element, gamma response region, GRR, GRR, Fc gamma RI gene, STAT5A, 94-kD STAT5A
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:
 STAT5B, GRR element, enhancer element, gamma response region, GRR, GRR, Fc gamma RI gene, STAT5A, 94-kD STAT5A