4844
To further study the role of tTG in liver disease , we initiated investigations into the effect of a proinflammatory mediator , tumor necrosis factor ( TNF ) - alpha , on tTG activity in cultured liver cells .
 GENE: tTG; GENE: tumor necrosis factor ( TNF ) - alpha; GENE: tTG
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 GENE: tTG; GENE: tumor necrosis factor ( TNF ) - alpha; GENE: tTG