BBS9 and chronic obstructive pulmonary disease: We aimed to determine the role of circRNA BBS9 in COPD progression.<h4>Methods</h4>Real-time quantitative reverse transcription PCR (qRT-PCR) was performed to determine the levels and the linkages of circRNA BBS9, miRNA-103a-3p, and BCL2L13 in cigarette smoke extract (CSE)-treated human pulmonary microvascular endothelial cells (HPMECs).