APLN and lung adenocarcinoma: In the present study, to further explore the function of apelin in the miR‐195‐mediated tumor suppressive behavior of lung adenocarcinoma cells, short hairpin RNA targeting apelin mRNA (si‐apelin) was used to specifically inhibit apelin expression, while the apelin/pcDNA3.0 vector was exploited to overexpress apelin in A549 cells.