14650
1,25-dihydroxy vitamin D3 and 12-O-tetradecanoyl phorbol-13-acetate ( TPA ) interact synergistically to induce monocytic differentiation of U937 histiocytic lymphoma cells .
 U937 histiocytic lymphoma cells
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:
 U937 histiocytic lymphoma cells