Background Pulmonary artery smooth muscle cell (PASMC) proliferation plays an important role in pulmonary vessel structural remodelling At present, the mechanisms related to proliferation of PASMCs are not clear Focal adhesion kinase (FAK) is a widely expressed nonreceptor protein tyrosine kinase Recent research indicates that FAK is implicated in signalling pathways which regulate cytoskeletal organization, adhesion, migration, survival and proliferation of cells Furthermore, there are no reports about the role of FAK in human pulmonary artery smooth muscle cells (HPASMCs) We investigated whether FAK takes part in the intracellular signalling pathway involved in HPASMCs proliferation and apoptosis, by using antisense oligodeoxynucleotides (ODNs) to selectively suppress the expression of FAK protein Methods Cultured HPASMCs stimulated by fibronectin (40 μg/ml) were passively transfected with ODNs, sense FAK, mismatch sense and antisense FAK respectively Expression of FAK, Jun NH2 terminal kinase (JNK), cyclin dependent kinase 2 (CDK 2) and caspase 3 proteins were detected by immunoprecipitation and Western blots Cell cycle and cell apoptosis were analysed by flow cytometry In addition, cytoplasmic FAK expression was detected by immunocytochemical staining Results When compared with mismatch sense group, the protein expressions of FAK, JNK and CDK 2 in HPASMCs decreased in antisense FAK ODNs group and increased in sense FAK ODNs group significantly Caspase 3 expression upregulated in HPASMCs when treated with antisense ODNs and downregulated when treated with sense ODNs When compared with mismatch sense ODNs group, the proportion of cells at G 1 phase decreased significantly in sense ODNs group, while the proportion of cells at S phase increased significantly In contrast, compared with mismatch sense ODNs group, the proportion of cells at G 1 phase was increased significantly in antisense FAK ODNs group The level of cell apoptosis in antisense FAK group was higher than in the mismatch sense group and the latter was higher than sense FAK group In addition, the sense FAK ODNs group was strongly stained by immunocytochemistry, whereas the antisense FAK ODNs group was weakly stained Conclusions The results suggest that FAK relates to the proliferation of HPASMCs Antisense FAK ODNs inhibit HPASMCs proliferation and facilitate their apoptosis It is possible that FAK via JNK, CDK 2 signalling pathways enhances HPASMCs proliferation and via caspase 3 inhibits HPASMCs apoptosis Background Pulmonary artery smooth muscle cell (PASMC) proliferation plays an important role in pulmonary vessel structural remodeling At present, the mechanisms related to proliferation of PASMCs are not clear Focal adhesion kinase (FAK) is a widely expressed nonreceptor protein tyrosine kinase Recent research that that FAK is implicated in signaling pathways which regulate cytoskeletal organization, adhesion, migration, survival and proliferation of cells Furthermore, there are no reports about the role of FAK in human pulmonary artery smooth muscle cells (HPASMCs) We asked whether FAK takes part in the intracellular Signaling pathway involved in HPASMCs proliferation and apoptosis, by using antisense oligodeoxynucleotides (ODNs) to selectively suppress the expression of FAK protein Methods Cultured HPASMCs stimulated by fibronectin (40 μg / ml) were passively transfected with ODNs, sense FAK, mismatch sense and antisense FAK respectively Expressi on of FAK, Jun NH2 terminal kinase (JNK), cyclin dependent kinase 2 (CDK2) and caspase 3 proteins were detected by immunoprecipitation and Western blots Cell cycle and cell apoptosis were analyzed by flow cytometry In addition, cytoplasmic FAK expression was detected by immunocytochemical staining results when compared with mismatch sense group, the protein expressions of FAK, JNK and CDK 2 in HPASMCs decreased in antisense FAK ODNs group and increased in sense FAK ODNs group expressed significantlyregulated in HPASMCs when treated with antisense ODNs and downregulated when treated with sense ODNs When compared with mismatch sense ODNs group, the proportion of cells at G 1 phase decreased significantly in sense ODNs group, while the proportion of cells at S phase increased significantly in contrast, compared with mismatch sense ODNs group, the proportion of cells cells at G 1 phase was increased significantly in antisense FAK ODNs group The level of cell apoptosis in antisense FAK group was higher than in the mismatch sense group and the latter higher than sense FAK group In addition, the sense FAK ODNs group was strongly stained by immunocytochemistry, whereas the antisense FAK ODNs group was weakly stained Conclusions The results suggests that FAK relates to the proliferation of HPASMCs Antisense FAK ODNs inhibit HPASMCs proliferation and facilitate their apoptosis It is possible that FAK via JNK, CDK 2 signaling pathways enhances HPASMCs proliferation and via caspase 3 inhibits HPASMCs apoptosis