Provided is a novel soluble factor that modulates morphogenesis and cell proliferation, such as cardiac development and/or cardiomyocyte differentiation. Specifically provided are: an inhibitor of Wnt signalling, comprising an insulin-like growth-factor-binding protein (IGFBP), the protein being binding to a Wnt receptor, and/or a polynucleotide encoding the protein； a medicament for prevention and/or treatment of a disease due to enhanced Wnt signalling, comprising the inhibitor of Wnt signalling, and a medicament for induction of cardiomyocyte differentiation； and a method for prevention and/or treatment of a disease due to enhanced Wnt signalling and a method of inducing cardiomyocyte differentiation, the methods each comprising using the inhibitor of Wnt signalling, and a cardiomyocyte, which is obtained by the method of inducing cardiomyocyte differentiation, and a use thereof.
