A. Treatment protocols for MCF7 cells with kynurenine (Kyn) or 2-hydroxyglutarate (2-OHG) in Dox-treated cells. Dox-treated cells without (−) and with (+) added Kyn (10 μM) were evaluated for apoptotic status (B), cell viability (C), and mammosphere-formation ability (D). Results (mean ± SEM) are from 3 independent experiments. For C and D, each experiment was conducted in quadruplicates. *P < 0.05 between treatment groups. Dox-treated cells were similarly treated with 2-OHG (10 μM) and analyzed for apoptotic status (E), cell viability (F), and mammosphere-formation ability (G), following described protocols (A). Results (mean ± SEM) are from 3 independent experiments. For F and G, each experiment was conducted in quadruplicates. *P < 0.05 between treatment groups.