Confirmation of miR-98 functions by targeting ALK1 in PASMCs. (A) Representative FACS analysis of Annexin V and PI staining of PASMCs following transfection with miR-98 mimics and lenti-ALK1 particles, and subsequent exposure to hypoxia for 24 h. (B) Percentage of apoptotic cells analyzed by FACS. (C) Cell Counting Kit-8 assay was used to analyze PASMC proliferation following transfection of PASMCs and exposure to hypoxia for 72 h. (D) Upper panel, western blot analysis of phosphorylated Smad1 and total Smad1; lower panel, western blot analysis of ALK1, cleaved caspase 3 and PCNA levels in PASMCs transfected with miR-98 mimics and ALK1 overexpression vector and subsequent exposure to hypoxia for 24 h. Densitometric analysis of (E) PCNA and (F) cleaved caspase 3 levels. All experiments were repeated 3 times. **P<0.01. miR, microRNA; ALK1, activin receptor-like kinase-1; PASMCs, pulmonary artery smooth muscle cells; PI, propidium iodide; NS, not significant; CCK-8, Cell Counting Kit-8; lenti-ALK1, ALK1 overexpression vectors carrying lentiviral particles; FACS, fluorescence-activated cell sorting; PCNA, proliferating cell nuclear antigen.