13420
These observations demonstrate that CD4 signaling mediates HIV-induced apoptosis by a mechanism independent of Fas -Fas ligand interaction , does not require p56(lck) signaling , and may involve a critical region for CD4 dimerization .
 protein: CD4; protein: p56(lck); protein: Fas; protein: -Fas ligand; protein: CD4
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: CD4, p56(lck), Fas, -Fas ligand, CD4 
Answer:
 protein: CD4; protein: p56(lck); protein: Fas; protein: -Fas ligand; protein: CD4