ABCG2 and cancer: These compounds have cytotoxic activity (EC50 = 3.6–111 μM) against diverse cancer cell lines from the breast, colon, lymphatic tissue, brain, and skin, which includes drug‐resistant phenotypes that either overexpress ABC transporters (P‐glycoprotein and BCRP), have activating mutations in EGFR or B‐RAF, or have p53 deleted.