ABCB1 and neoplasm: Specifically, EVs from drug-resistant tumor cells can horizontally transfer various components, such as drug-efflux pumps (e.g., ABCB1, ABCC1), miRNAs (e.g., miR-21-5p, miR-222), and regulatory proteins (e.g., TrpC5, EGFR), to drug-sensitive cells, thereby spreading a drug-resistant phenotype.