TGFB1 and allergic asthma: TGF-β signaling has previously been shown to induce apoptosis in airway epithelial cells that indicate TGF-β contributes to the airway epithelial layer damage in the asthmatic airway [16] However, the exact function of TGF-β in airway epithelium other than induction of apoptosis during the development of allergic asthma remains unclear.