| We now show that receptor induced tyrosine phosphorylation of NTAL and concomitant Grb 2 complex formation critically modulate the Ca ( 2+ ) response without affecting SLP 65 and PLC gamma 2 phosphorylation . ^^^ Thus , elevation of Ca ( 2+ ) is regulated by at least two signaling modules , the B cell specific Ca ( 2+ ) initiation complex comprising SLP 65 , Btk , and PLC gamma 2 and the more ubiquitously expressed NTAL / Grb2 complex , which acts as an amplifier by switching off inhibitory elements . . ^^^ |