tokens: However , coligation of Fc gamma RIIB1 with B cell Ag receptors ( BCR ) inhibits BCR - mediated signaling by a mechanism that may involve recruitment of phosphatases SHP - 1 , SHP - 2 , and the SH2 containing inositol 5 ' phosphatase ( SHIP ) to the phosphorylated Fc gamma RIIB1 immunoreceptor tyrosine - based inhibitory motif .