Effects of Oncostatin M on expression of endogenous AAT in the 16HBE cell line. Nontransfected 16HBE cells were cultured in the absence (OsM-) or presence (OsM+) of 50 ng/ml Oncostatin M for 24 hours, and AAT mRNA expression and AAT protein secretion were analyzed. ( A ) Mean AAT mRNA expression levels, normalized for β-actin expression levels (×103), as measured by real-time PCR analysis from total cellular RNA. ( B ) AAT protein levels as measured by ELISA for total AAT in cell culture media. The fold increase in expression of Oncostatin M-treated versus untreated cells is indicated. Results are expressed as mean ± SEM (n = 3–4). *P < 0.05 Student’s t-test. Definition of abbreviations: AAT = alpha-1 antitrypsin; ELISA = enzyme-linked immunosorbent assay; mRNA = messenger ribonucleic acid; Real-time PCR = reverse transcription real-time polymerase chain reaction; RNA = ribonucleic acid.