To verify whether downregulation of FGF15 could explain why PIEZO1 knockout in IEC alleviated HFD-induced liver steatosis, exogenous recombinant human FGF19 protein was supplemented to HFD-fed Piezo1ΔIEC mice for 4 weeks (Fig. 4A). The gene discussed is PIEZO1; the disease is Hepatic steatosis.