To investigate how phenformin protected against tumorigenesis in an AMPK-dependent manner, we tested effects of biguanides on tumor cell viability in vitro, both with primary PTEN-null T-ALL cells from this project and with three previously established PTEN-null T-ALL lines (M100, F04, and F15). The gene discussed is PRKAA1; the disease is acute lymphoblastic leukemia.