7426
Importantly, it was also present in the nucleus of HeLa cells , which lack HNF1 , and in the cytoplasm of fibroblasts that have little or no tetrahydrobiopterin .
 ( cell type: fibroblasts, None) , ( cell line: HeLa cells, None) , ( protein: HNF1, None) , ( protein: tetrahydrobiopterin, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( cell type: fibroblasts, None) , ( cell line: HeLa cells, None) , ( protein: HNF1, None) , ( protein: tetrahydrobiopterin, None) 