5987
Prior studies have shown MCP-1 expression is modulated by a variety of ligands that act through extracellular receptors .
 protein: extracellular receptors; protein: MCP-1
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
 Entities: extracellular receptors, MCP-1 
Answer:
 protein: extracellular receptors; protein: MCP-1