In laryngeal cancer, knockdown of circ_0004507 reduces the protein levels of multidrug resistance-associated protein-1 (MRP1) and multidrug resistance gene 1 (MDR1), which are associated with cellular cassette transporters and confer multidrug resistance to tumor cells by reducing the uptake of anticancer drugs (86). This evidence concerns the gene ABCC1 and laryngeal carcinoma.