Semiquantitative analysis of human procollagen I staining in mice exposed to hypoxic conditions demonstrated that knockdown of GPR81 in IPF MPCs decreased human procollagen I staining in the mouse lungs by 40% compared with mice exposed to hypoxia and receiving IPF MPCs transduced with scrambled control (Figure 8X). The gene discussed is HCAR1; the disease is idiopathic pulmonary fibrosis.