On the other hand, the presence of VM ductal structures was detected in 57% of Wnt3a-positive NSCLC tissues, whereas the presence of VM channels was detected in only 8% of Wnt3a-negative samples, and further knockdown of Wnt3a expression in H1299 and A549 cell lines overexpressing TOP2A significantly inhibited their formation of VM ductal structures in vitro, so we believe that Wnt3a is essential in the formation of VM in NSCLC. The gene discussed is TOP2A; the disease is non-small cell lung carcinoma.