The present invention describes a newly discovered full-length polynucleotide encoding an SH2/SH3 domain-containing adapter protein, called hSLAP-2, cloned, isolated and identified. Also described are the hSLAP-2 polypeptide sequence, expression vectors, host cells, agonists, antagonists, anti-sense molecules, and antibodies related to the polynucleotide and/or polypeptide of the present invention. Methods for screening for modulators, particularly inhibitors, of the hSLAP-2 protein and use of the hSLAP-2 polynucleotide and polypeptide for therapeutics and diagnostics are described.