ADRB2 and chronic obstructive pulmonary disease: At baseline (no IL-13 treatment), bronchial epithelial cell ADRB2 mRNA levels were not (p = 0.15) significantly different among normal subjects (ADRB2 mRNA relative level: 15.0 ± 2.5), asthmatics (8.6 ± 2.3) and COPD patients (13.8 ± 2.3).