passages.id: split_4_test_884_passage
passages.type: progene_text
passages.text: BCR cross - linking activates three families of non - receptor protein tyrosine kinases ( PTKs ) and these are transducers of signaling events including phospholipase C and mitogen - activated protein kinase activation ; however , the relative roles of PTKs in BCR - mediated Akt activation are unknown .