ZEB2 and lung cancer: miR-222 downregulates the cyclin-dependent kinase (CDK) inhibitors p27Kip1 and p57 and upregulates the epithelial-to-mesenchymal transition gene ZEB2, with changes being developed as a liquid biopsy for early-stage NSCLC [27,28], miR-221 promotes apoptosis of NSCLC cells through negative regulation of lncRNA HOTAIR [29], and miR-9 promotes lung cancer cell invasion and adhesion [30].