ABCG2 and neoplasm: For instance, overexpression of ABC transporters such as P-gp and BCRP has been associated with upregulation of DNA repair proteins (e.g., BRCA1/2), altered expression of apoptotic regulators (e.g., Bcl-2, caspases), and increased glycolytic activity that sustains tumor cell survival under therapeutic stress (Gottesman, Fojo & Bates, 2002).