RBFOX1 and heart failure: As a result of the rbfox1 knockdown, 85% of the zebrafish embryos injected with MO1 (n=159; Fig. 2D) and 72% of those injected with MO2 (n=100, Fig. 2E) developed progressive heart failure due to continually decreasing ventricular contractility as measured by fractional shortening (Fig. 2B,C; supplementary material Movie 2).