For example, pulmonary fibroblasts from IPF patients have spontaneously elevated levels of IL-13 and IL-4 receptor subunits, and it has been suggested that the abnormal proliferative properties of lung fibroblasts from certain lung fibrosis patient groups can be modulated in a manner that is dependent on the IL-4 and IL-13 receptor expression [10]. The gene discussed is IL13; the disease is idiopathic pulmonary fibrosis.