ABCG2 and lung cancer: Although there are still many difficult problems, including many miRNAs have been found to be abnormally expressed in lung cancer, but their functional characteristics and significance still need to be further confirmed; the specific roles of these miRNAs in different subtypes of lung cancer may be different; the miRNAs found to regulate the ABC transporter in chemotherapy-resistant cancers are just the tip of the iceberg of the gene transcripts, and how to combine the miRNAs with anti-cancer drugs for efficient treatment deserves attention.