Combinatorial therapy for drug-resistant cancers: A therapeutic mix encompassing Metformin and Navitoclax (ABT-263) (MAN) inhibits the expression of phospholipid glutathione peroxidase (GPX4), inhibits GPX4 signaling network and lipid peroxidase pathway, suppresses EMT protein ZEB1, increases sensitivity to anticancer therapy and prolongs survival via upregulation of its target gene, 3/February/2019, 10.58 pm