801
Gel electrophoresis mobility shift assays and DNaseI footprinting assays demonstrate that these negative regulatory sequences are recognized differently by proteins present in nuclear extracts obtained from HeLa and K562 cells .
 cell line: HeLa; cell line: K562 cells; protein: proteins; protein: DNaseI
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 cell line: HeLa; cell line: K562 cells; protein: proteins; protein: DNaseI