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Here we demonstrate that the endogenous thyroid hormone receptor alpha ( c-erbA/TR-alpha ) and the closely related retinoic acid receptor alpha ( RAR-alpha ) play a role in the regulation of normal erythroid differentiation .
 protein: thyroid hormone receptor alpha; protein: RAR-alpha; protein: retinoic acid receptor alpha; protein: c-erbA/TR-alpha
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 protein: thyroid hormone receptor alpha; protein: RAR-alpha; protein: retinoic acid receptor alpha; protein: c-erbA/TR-alpha