YF479 inhibits breast tumor cell growth in vitro. (A) MDA-MB231, 4 T1 and T47D cells were treated with indicated concentrations of YF479 for 48 hours. Cell viability was assessed by MTS assay (n = 3). (B) MDA-MB231, 4 T1 and T47D cells were treated with 5 μM YF479 or 5 μM SAHA for 24 hours. Cell cycle distribution was then evaluated using propidium iodide (PI) staining and flow cytometry (n = 3). (C) MDA-MB231, 4 T1 and T47D cells were treated with indicated concentrations of YF479 and 5 μM SAHA for 48 hours. Apoptosis was assessed by Annexin V/PI staining and flow cytometry (n = 3). (D) YF479 and SAHA abrogate cancer cell colony formation capacity (8 days). Number of colonies counted in experiments repeated three times. Results represent the average of three replications. (E) MDA-MB231, 4 T1 or T47D cells were incubated with various concentrations of YF479 and 5 μM SAHA for 48 hours. Effects on the expression of PCNA, p21, caspase 3, cleaved –caspase 3, PARP and cleaved-PARP were determined by western blot. Actin was used as a loading control. **P < .01; ***P < .001.