Next, immunoblotting was performed to determine the protein expression of ABCG2 in ABCG2-overexpressing NCI-H460/MX20 and A549-Bec150 cancer cells treated with DMSO (control), or increasing concentrations of hydroxygenkwanin (0.1–1.0 μM), for 72 h, as detailed in the Section 4 (Figure S1). Here, ABCG2 is linked to cancer.