For example, the in vitro expression of OCT1 and OCT2 decreases upon activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway in vitro (cell-line systems) [72,73], and the expression of OCT1 and OCT2 decreases upon induction of diabetes in streptozotocin-inducable diabetic rats in vivo [74]. This evidence concerns the gene AKT1 and diabetes mellitus.