Cytokine-mediated signal transduction in the JAK-STAT cascade requires the involvement of adaptor molecules. One such signal-transducing adaptor molecule contains an SH3 domain that is required for induction of MYC and cell growth. The protein encoded by this gene binds to the SH3 domain of the signal-transducing adaptor molecule, and plays a critical role in cytokine-mediated signaling for MYC induction and cell cycle progression. Multiple alternatively spliced transcript variants encoding the same protein isoform have been found for this gene. [provided by RefSeq, Jul 2008].