passages.id: split_4_test_792_passage
passages.type: progene_text
passages.text: The requirement for Fyn , Lck , and ZAP-70 is not due to tyrosine phosphorylation of 70Z Cbl , as mutation of all tyrosines in , or deletion of , the C - terminal region of 70Z Cbl ( amino acids 655 to 906 ) blocks 70Z Cbl tyrosine phosphorylation but enhances 70Z Cbl - mediated NFAT activation .