IL13 and asthma: In addition, TGFβ1 upregulation in airway epithelial cells occurs by mechanical stress that mimics bronchocontriction [113], as well as in several in vivo conditions in addition to the aforementioned animal models of asthma [54,56,98], including IL-13 transgenic mice [16], and advanced pulmonary fibrosis [114] and COPD [112] in humans.