Figure 2.

Propranolol (PRO) and naltrexone (NTX) produce synergistic effects on reduction in breast tumor cell viability. Cells were cultured in the presence of the indicated doses of a single drug (NTX or PRO) or drug combination (NTX + PRO) on viability of MDA-MB-231 cells (A–C), MDA-MB-468 cells (D–F), and T47D cells (G–I) after 24, 48, and 72 h. Cell viability was analyzed by MTT assay and data presented as mean ± SEM (n = 12). The values of the inhibitory concentration required to arrest 50% of the cells (IC50) were calculated and presented in (J).