4408
It has been shown in experiments in vitro that the hepatotrophic organic anions , the radiographic contrast agent ( RCA ) bilignost used in cholecystography and Bengal pink , have an affinity , unlike the urographic RCA triombrin and renotrophic dye indigo - carmine , for the plasmatic membranes ( PM ) of liver cells .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
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