4321
NIK - 247 , tacrine and E - 2020 all strongly inhibited acetylcholinesterase ( AChE ) in human red blood cells ( IC50s = 1 . 0 x 10 ( - 6 ) , 2 . 9 x 10 ( - 7 ) and 3 . 7 x 10 ( - 8 ) M , respectively ) .
 Chemical: NIK - 247; Chemical: tacrine; Chemical: E - 2020
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: NIK - 247; Chemical: tacrine; Chemical: E - 2020