Compositions and methods for treatment of non-Hodgkin's lymphoma

A method for inhibiting the growth of a non-Hodgkin's lymphoma cell in vitro that overexpresses a polypeptide, wherein the polypeptide comprises an amino acid sequence selected from (i) the amino acid sequence of SEQ ID NO:2, (ii) the amino acid sequence of SEQ ID NO:2, lacking its siginal peptide, and (iii) an amino acid sequence resulting from enzymatic cleavage of (i) or (ii) with a proprotein convertase, the method comprising contacting the non-Hodgkin's lymphoma cell with an antibody that (a) specifically binds to the polypeptide that is bound to the surface of the non-Hodgkin's lymphoma cell and (b) does not inhibit binding of the polypeptide to the non-Hodgkin's lymphoma cell, and wherein the antibody is conjugated to a therapeutic agent that inhibits the growth of the non-Hodgkin's lymphoma cell.