Moreover, a previous study indicated that inhibitors of the bile-acid transporter gene ATP-binding cassette subfamily G member 2 (ABCG2), such as genistein and isoflavone, reduce the fluorescence intensity of PPIX in brain tumor cells, suggesting that activating bile-acid transporter genes may enhance the cellular efflux of PPIX accumulated in hepatic cells, thereby protecting against liver injury [12]. The gene discussed is ABCG2; the disease is brain neoplasm.