ABCC1 and glioblastoma: One of the molecules identified as a chemo-sensitizing agent is the immunosuppressive drug tacrolimus (FK506), which at subtherapeutic concentrations (15 ng/mL) decreases both the expression and activity of MRP1 in GBM differentiated cells (non-GSCs), promoting chemo-sensitization to the antitumoral drug Vincristine (Vc) [19].