3535
We explored the role of ER - stress as a general mechanism of toxicity by utilizing a high - throughput in vitro assay to screen 316 chemically diverse Pfizer proprietary compounds with known in vivo toxicity outcome for nuclear accumulation of spliced x - box binding protein 1 ( XBP1s ) , a key transcription factor of the unfolded protein response ( UPR ) .
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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:
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