3
Delineation of the CD28 signaling cascade was found to involve protein tyrosine kinase activity , followed by the activation of phospholipase A2 and 5-lipoxygenase .
 ( protein: 5-lipoxygenase, None) , ( protein: phospholipase A2, None) , ( protein: CD28, None) , ( protein: protein tyrosine kinase, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( protein: 5-lipoxygenase, None) , ( protein: phospholipase A2, None) , ( protein: CD28, None) , ( protein: protein tyrosine kinase, None) 