HOXA9 and non-small cell lung carcinoma: The vectors for CircRNA CDR1as downregulation (Fig. 4a), miR-641 inhibitor (Fig. 4b) and HOXA9 overexpression (Fig. 4c) were next pre-transfected into DDP-resistant NSCLC cells (A549/DDP, H1299/DDP and Calu6/DDP), and the cells were subsequently exposed to high-dose DDP stimulation.