〔Abstract〕 Objective To explore the effect ofMPZL1knockdown in A549 Taxol resistant(A549/Tax) cells and whether it affect drug resistance and tumor cell stemness by regulating β-catenin. Methods A549 and A549/Tax cells were treated with different concentrations of doxorubicin and paclitaxel to observe the differences in drug resistance between the two cells. Quantitative real-time PCR(qRT-PCR) and Western blot were used to detect the MPZL1 expression level in A549 and A549/Tax cells. After knockdown or overexpression ofMPZL1in A549/Tax cells, cells were divided into control group, small hairpin RNA negative control(sh-NC) group,MPZL1knockdown(sh-MPZL1) group, overexpression negative control(OE-NC) group,MPZL1overexpression(OE-MPZL1) group. Cell counting kit-8(CCK-8) and clone formation assay were utilized to investigate cell proliferation and clone formation ablity. Western blot assay was used to detect the protein expression after the cells treated with Wnt/β-catenin signaling inhibitor XAV939 and activator CHIR-99201. Results The half inhibitory concentration(IC50) of doxorubicin and paclitaxel in A549/Tax cells significantly increased compared to A549 cells(P<0.01). MPZL1 presented a higher expression trend in A549/Tax cells. The IC50values of A549/Tax for doxorubicin and paclitaxel were 2.731 mg/ml and 4.939 μg/ml afterMPZL1knockdown, compared to 4.541 mg/ml and 13.55 μg/ml in the NC group(P<0.01). The results of CCK-8 and clone formation assay showed that the knockdown ofMPZL1reduced the viability of cells proliferation and clonal formation ability(P<0.05). Western blot results indicated that the expression levels of MPZL1 protein, tumor cell stemness associated proteins(CD44, CD133), β-catenin and multidrug resistance protein 1(MDR1), lung resistance-related protein(LRP) were significantly reduced in the sh-MPZL1 group. Furthermore, XAV939 could inhibit the expression levels of MPZL1, CD44, CD133, MDR1, LRP and β-catenin(P<0.01). The inhibitory effect of knockdownMPZL1on the aforementioned proteins was significantly reversed by CHIR-99201 treatment. Conclusion MPZL1 is highly expressed in A549/Tax cells. KnockdownMPZL1suppresses the tumor cell stemness and proliferation, thereby reversing the drug resistance of doxorubicin and paclitaxel in A549/Tax cells.