In fact, an experimental study has shown that paricalcitol attenuated the cardiac hypertrophy and fibrosis [14], by reducing collagen I, TGF-β1 and increasing MMP1, an interstitial collagenase that degrades type I, II, and III structural collagens, favoring the reduction of collagen [14,171]. The gene discussed is MMP1; the disease is cardiac hypertrophy.