7569
Differential inhibition of Smad6 and Smad7 on bone morphogenetic protein- and activin- mediated growth arrest and apoptosis in B cells .
 B cells, Smad7, Smad6
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:
 B cells, Smad7, Smad6