POSTN and asthma: The current biomarkers of asthma mediated by the so-called T2 pathway [Th2 and ILC2 (group 2 innate lymphoid cells)] (2–4) include eosinophils in sputum and peripheral blood, the exhaled fraction of nitric oxide (FeNO), serum total IgE, specific IgE/skin prick tests to common aeroallergens, and more recently periostin.