Final answer:
ABC-type ATPases that transport antitumor drugs out of tumor cells and reduce the effectiveness of these drugs are known as multidrug resistance (MDR) transporters, which are similar to efflux pumps in bacteria that export antimicrobial drugs.
Step-by-step explanation:
ABC-type ATPases that inhibit the effectiveness of antitumor drugs by transporting the drugs out of tumor cells are known as multidrug resistance (MDR) transporters. These transporters are a form of efflux pumps that actively export a variety of drugs from the cells, making them less vulnerable to the therapeutic effects of the drugs. This mechanism is similar to the efflux pumps found in negative pathogenic bacteria that actively transport an antimicrobial drug out of the cell to prevent the accumulation to antibacterial levels.
In the context of anticancer treatment, the presence of these MDR transporters can lead to the development of drug resistance, where tumor cells are able to pump out therapeutic drugs, reducing their intracellular concentration and thus their efficacy. This is one of the challenges in cancer therapy, as it can make tumors resistant to a range of chemotherapeutic agents.