6698
When chronically applied to the skin , they supposedly would not damage normal skin cells or negatively affect their functions while they would suppress tumorigenic cell transformation , inhibit tumor cell proliferation , and activate tumor cell apoptosis .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None