Protein having antitumor activity

Claim 1

A protein having an antitumor activity comprising a polypeptide subunit having an N-terminal amino acid sequence of the following formula (I): Ser-Ala-Ser-Arg-Ala-Leu-Ser-Asp-Lys-Pro-Leu-Ala-His-Val-Val-Ala-Asn-Pro-Gln-Val-Glu-Gly-Gln-Leu-Gln-Trp-Leu- wherein Ala stands for alanine residue, Arg an arginine residue, Asn an asparagine residue, Asp an aspartic acid residue, Gln a glutamine residue, Glu a glutamic acid residue, Gly a glycine residue, His a histidine residue, Leu a leucine residue, Lys a lysine residue, Pro a proline residue, Ser a serine residue, Trp a tryptophan residue and Val a valine residue; and which protein has: (a) a molecular weight of 40,000±5,000 in terms of a value as measured by a gel filtration method as defined herein and a molecular weight of 17,500±2,000 in terms of a value as measured by an SDS-polyacrylamide gel electrophoresis method as defined herein; and (b) an isoelectric point of 5.0±0.3 in terms of a value as measured by an isoelectric focusing method as defined herein.