ABCG2 and esophageal cancer: Several genes/pathways have been implicated to esophageal cancer migration, such as Cdc42 [26], HGF/SF [27], Androgen receptor [28], RhoA, Rac-1, and Cdc42 [29], VEGF [30], HER2 [31], PLCE1 [32], ABCG2/V-ATPase, MMS19 [33].