GAB2 have multiple tyrosyl phosphorylation sites that are phosphorylated up on activation of FCERI. SYK is the major tyrosine kinase involved in GAB2 phosphorylation. FYN is also shown to contribute to GAB2 tyrosyl phosphorylation but it is not clear whether GAB2 is a direct substrate of FYN (Yu et al. 2006, Parravicini et al. 2002). GAB2 tyrosines (Y452, Y476 and Y584) in the YXXM motif can be the target phosphorylation sites for SYK/FYN kinases (Chan et al. 2010, Harir et al. 2007).