In regard to studies performed on human PCLSs, Stephenson et al. [33] stimulated PCLSs (derived from a healthy donor as well as a donor with idiopathic pulmonary fibrosis) with IL-33 or TGFβ and then tested whether this combination would affect lung fibrosis-related gene expression. The gene discussed is TGFB1; the disease is idiopathic pulmonary fibrosis.