Semaphorin polypeptides

A method comprising assaying the binding of a DCSema polypeptide to a VESPR protein wherein the DCSema polypeptide comprises an amino acid sequence at least 80% identical to amino acids 45-666 of SEQ ID NO:2, wherein the percent identity is calculated using the GAP program with a unary comparison matrix, a 3.0 gap penalty, an additional 0.10 penalty for each symbol in each gap, and no penalty for end gaps.