6942
An expression library was constructed by inserting 5 ' portion - enriched cDNAs from phytohemagglutinin - stimulated peripheral blood mononuclear cells into upstream of signal sequence - deleted CD4 cDNA in an Epstein - Barr virus shuttle vector .
 phytohemagglutinin, signal sequence - deleted CD4 cDNA
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 phytohemagglutinin, signal sequence - deleted CD4 cDNA