The greatly elevated concentration of eATP plays much larger and diverse roles than previously realized in augmenting drug resistance in cancer cells through internalization[6-8], promoting cell survival[6-9], accelerating ATP-binding cassette (ABC) transporter activities[10,11], inducing epithelial-mesenchymal transition (EMT)[12] and possibly the formation of cancer stem cells (CSC). The gene discussed is ABCG2; the disease is cancer.