HMOX1 and breast cancer: Another study shows that luteolin reduces the mRNA levels of phase 2 drug detoxifying enzymes, such as HO-1, NQO-1, aldo-keto reductases1 C1 and C2 (AKR1C), glutamate-cysteine ligase catalytic subunit (GCLC), and multidrug resistance-associated protein (MRP) 2 in human cancer cells, A549, siGFP-C5 (a stable lung cancer cell line developed from A549 cells by transfecting pRS-GFP), Caco-2 cells, and human breast cancer MCF7 cells [61].