In addition, microstructural examinations, including hematoxylin-eosin (H&E) staining, Masson’s trichrome staining, and wheat germ agglutinin (WGA) staining, all revealed pathological myocardial hypertrophy in Clk4-cKO mice, as evidenced by enlarged left ventricles (Fig. 3a–c), increased myocyte size by cardiomyocyte cross-sectional area (CSA), without a significant change in the myocyte length (Fig. 3d–g) and elevated amounts of interstitial fibrosis (Fig. 3h, i). The gene discussed is CLK4; the disease is cardiac hypertrophy.