pure dna also includes a recombinant dna which is part of a hybrid gene encoding april u201c biologically active u201d as used herein means having an in vivo or in vitro activity which may be performed directly or indirectly biologically active fragments of april may have for example 70 amino acid homology with the active site of april more preferably at least 80 and most preferably at least 90 homology identity or homology with respect to april is defined herein as the percentage of amino acid residues in the candidate sequence which are identical to the april residues in seq id nos 2 or 4 u201c ligand u201d as used herein generically refers to april the practice of the present invention will employ unless otherwise indicated conventional techniques of cell biology cell culture molecular biology transgenic biology microbiology recombinant dna and immunology which are within the skill of the art such techniques are described in the literature april a novel member of the tnf family is described in detail herein the inventors have found that while transcript of april are of low abundance in normal tissues high levels of mrna are detected in several tumor cell lines as well as in colon carcinomas metastatic lymphomas and thyroid tumors in vitro the addition of recombinant april stimulates the proliferation of various cell lines moreover transfection of april into nih 3t3 cells dramatically accelerated tumor growth in nude mice when compared to.