Abstract： Objective To investigate the effect of MRPL21 and YAP1/TAZ pathway on the activity of non-small cell lung cancer A549 cells,so as to provide new ideas for the treatment of non-small cell lung cancer.Methods Non-small cell lung cancer tissues and adjacent tissues were obtained from 9 patients with non-small cell lung cancer who underwent surgical treatment in the First Affiliated Hospital of Anhui Medical University between June,2021 and September,2023.The expression of MRPL21 in the tissues was analyzed by immunohistochemistry.A549 cells were ran-domly divided into three groups:siNC group,siMRPL21 group and BPD-MA group.CCK-8 assay and Hoechst staining were used to detect the proliferation of A549 cells.Transwell assay was used to analyze the invasion ability of A549 cells.TUNEL staining was used to detect the apoptosis of A549 cells.Western blotting assay was used to detect the expression levels of MRPL21,YAP1 and TAZ proteins in A549 cells.Results The results of immunohistochemistry showed that the expression of MRPL21 was up-regulated in the non-small cell lung cancer tissues compared with that in the adja-cent tissues(P<0.05).Compared with the A549 cells in the siNC group,cells in the siMRPL21 group and the BPD-MA group showed decreased proliferation ability as detected by CCK8 assay and Hoechst staining assay(P<0.05).Transwell assay showed that the invasion abilities of A549 cells in the siMRPL21 group and the BPD-MA group were decreased(P<0.05).TUNEL staining showed that the apoptosis rates of A549 cells were increased in the siMRPL21 group and the BPD-MA group(P<0.05).Western blotting results showed that the siMRPL21 group and the BPD-MA group had significant reduced protein levels of YAP1 and TAZ in A549 cells(P<0.05).Conclu-sion MRPL21 is highly expressed in non-small cell lung cancer tissues.After inhibiting the expres-sion of MRPL21,the proliferation activity and invasion ability of A549 cells are weakened,and the apoptosis rate is increased,which is related to the regulation of YAP1/TAZ signaling pathway.MRPL21 is expected to be a new target for the treatment of non-small cell lung cancer.