NEW MATERIAL:The physiologically active polypeptide having amino acid sequence of formula.

USE: An antitumor agent having lymphotoxin(LT) activity.

PREPARATION: For example, an LT-producing cell is produced by the cell fusion of a normal human T-lymphocyte and a tumor cell. Whole RNA is extracted from the obtained cell e.g. by guanidine hydrochloride process and mRNA is separated e.g. by gelfiltration process. A complimentary cDNA is synthesized with a reverse transcriptase using the mRNA as template and is integrated into a proper plasmid to obtain a recombinant plasmid, which is inserted into E.coli, etc., to effect transformation of the cell and produce a cDNA library. The library is cloned with a synthetic probe and the cloned DNA is cut from the clone with a restriction enzyme and linked to a manifestation vector. The product is inserted into E.coli and cultured. The compound of formula can be separated from the cultured liquid.