ABCG2 and cancer: Many of their aberrant expressions are associated with angiogenesis, cell survival, resistance to cancer therapy, migration, etc. For example, as top-ranked CREB1-upregulated targets, STC2 and ABCG2 promote proliferation and metastasis of pancreatic cancer cells and hepatocellular carcinoma respectively [34, 35], while as top-ranked CREB1-downregulated targets, SERPINI1 and SEMA6A are lowly expressed and fail to exert tumor-suppressive effects in gastric and lung cancer cells respectively [36, 37].