An isolated polypeptide comprising an amino acid sequence at least 70% homologous to SEQ ID NO: 4 and an isolated polynucleotide encoding same are disclosed. A polynucleotide comprising a nucleic acid sequence capable of specifically hybridizing to the isolated polynucleotide and an isolated antibody comprising an antigen recognition domain which specifically binds the isolated polypeptide are also disclosed. Pharmaceutical compositions, methods of diagnosing and treating comprising same are also disclosed.