19783
The antitumor activity of these complexes against various tumor cells have been evaluated by MTT assay , and the results show that this type of arene Ru ( II ) complexes exhibit acceptable inhibitory effect against all of these tumor cells , especially osteosarcoma MG - 63 cells , but with low toxicity toward HK - 2 human normal cells .
 Chemical: MTT; Chemical: arene; Chemical: Ru ( II )
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: MTT, arene, Ru ( II ) 
Answer:
 Chemical: MTT; Chemical: arene; Chemical: Ru ( II )