Patent ID: 8105803

Claim:
A method for activating promotion of cardiomyocyte differentiation comprising administering, to a cardiomyocyte, a protein consisting of any one of the following amino acid sequences (a) to (c) and having an activity of promoting cardiomyocyte differentiation, or a recombinant vector comprising a DNA sequence encoding the protein and capable of expressing the protein in a cardiomyocyte: (a) an amino acid sequence wherein cysteine at position 138 is substituted with another amino acid in the amino acid sequence of SEQ ID NO:2; (b) an amino acid sequence wherein cysteine at position 138 is substituted with another amino acid and one or several amino acids other than cysteine at position 138 are deleted, substituted or added in the amino acid sequence of SEQ ID NO:2, wherein a protein consisting of the amino acid sequence has an inhibitory activity against dual specificity phosphatase; (c) an amino acid sequence having at least 90% or more identity to the amino acid sequence of SEQ ID NO:2 and having at position 138 an amino acid other than cysteine, wherein a protein consisting of the amino acid sequence has an inhibitory activity against a dual specificity phosphatase.