2449
Thrombin and thrombin receptor agonist peptide induce early events of T cell activation and synergize with TCR cross-linking for CD69 expression and interleukin 2 production.
 protein: TCR; protein: CD69; protein: Thrombin; protein: thrombin receptor
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: TCR, CD69, Thrombin, thrombin receptor 
Answer:
 protein: TCR; protein: CD69; protein: Thrombin; protein: thrombin receptor