DUSP4 and cardiomyopathy: However, targeted deletion of Dusp4 in mice as a single lesion is not known to generate spontaneous tumors of any kind, and these mice have mainly been used to study immunologic responses to inflammatory stimuli, such as infection [16] and cardiomyopathy, where combined deletion of both DUSP1 and DUSP4 is required for a cardiac phenotype [17].