In vitro and in vivo experiments have shown that nuciferine can overcome drug resistance to PTX and other chemotherapeutics by the modulation of PI3K/AKT/ERK pathways, which results in the suppression of Nrf2 and HIF-1α activation, as well as their downstream targets, P-gp and BCRP (Breast Cancer Resistance Protein) in PTX-resistant cell lines from colon and lung cancer. Here, ABCG2 is linked to lung cancer.