For example, constitutive overactivity of the PI3K/Akt pathway induces ABCB1 and ABCG2 expression and their associated proteins’ translocation to the plasma membrane of brain microvasculature endothelial cells, which increases drug resistance of brain tumors (Takada et al., 2005; Bleau et al., 2009b; Agarwal et al., 2011; Huang et al., 2013; Huang et al., 2014b). Here, ABCB1 is linked to brain neoplasm.