**Figure 3.** **Hsa_circ_0072309 reduction impaired tumorigenesis in cell lines.** (**A**) Real-time qPCR shows the expression level of hsa_circ_0072309 in lung cancer cells H1975 and its knockdown efficiency. (**B**) Cell proliferation assays of hsa_circ_0072309-knockdown H1975 cells. (**C**) Invasion capability analysis of hsa_circ_0072309-knockdown H1975 cells by Transwell assays. (**D**) Migration ability analysis of hsa_circ_0072309-knockdown H1975 cells by wound-healing assays. (**E**) Real-time qPCR shows the expression level of hsa_circ_0072309 in lung cancer cells H1650 and its knockdown efficiency. (**F**) Cell proliferation assays of hsa_circ_0072309-knockdown H1650 cells. (**G**) Invasion capability analysis of hsa_circ_0072309-knockdown H1650 cells by Transwell assays. (**H**) Migration ability analysis of hsa_circ_0072309-knockdown H1650 cells by wound-healing assays. Quantitative results are indicated in the right panel (**C**–**D**, **G**–**H**). Student’s *t*-test (**A**, **E**). Two-way ANOVA followed by Tukey’s multiple comparisons test (**B**–**D**, **F**–**H**). ^{*}*p* < 0.05, ^{**}*p* < 0.01, ^{***}*p* < 0.001.