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Our results reveal HRG1 as the long - sought heme transporter for heme - iron recycling in macrophages and suggest that genetic variations in HRG1 could be modifiers of human iron metabolism .
 Chemical: heme; Chemical: heme; Chemical: iron; Chemical: iron
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: heme; Chemical: heme; Chemical: iron; Chemical: iron