CCND1 and chronic obstructive pulmonary disease: The has_circ_0016070 is associated with vascular remodeling in pulmonary arterial hypertension (PAH) in COPD patients by promoting the proliferation of pulmonary artery smooth muscle cells (PASMCs) via the miR-942/Cyclin D1 (CCND1) axis; has_circ_0016070 significantly increased cell viability and decreased the number of cells arrested in the G1/G0 phase [15].