A multitude of studies have implicated GH action in tumor cells with intrinsic or acquired resistance to chemotherapy like cisplatin, doxorubicin, paclitaxel, Cyclophosphamide (CTX), mitomycin-C (MMC), and others; yet the involvement of membrane-spanning ATP-hydrolyzing multi-drug efflux pumps or ABC (ATP-binding cassette containing)-transporters were not investigated until recently. This evidence concerns the gene GH1 and neoplasm.