ABCG2 and neoplasm: For example, nuciferine, an alkaloid from Nelumbo nucifera and Nymphaea caerulea, down-regulated the P-gp and BCRP levels in the HCT-8/T and A549/T cells that resistant to paclitaxel by inhibiting the upstream nuclear factor erythroid 2-related factor 2 (Nrf2) and hypoxia-inducible factor 1-alpha (HIF-1α) via PI3K/AKT pathway, leading to enhanced tumor suppression effect in A549/T cell xenograft mice with combination treatment 79.