Effect of phenethyl isothiocyanate (PEITC) on MDA-MB-231 cells expressing high HER2 (HH). (A) Comparative effect of PEITC treatment on MDA-MB-231 cells with stable overexpression of HER2 relative to parent cells and vector control cells. Cells were treated for 24 h with 10 μM PEITC, and whole lysate was analyzed by western blotting for phosphorylated signal transducer and activator of transcription 3 (p-STAT3) (Y705) and cleavage of poly-ADP ribose polymerase (PARP). (B) MDA-MB-231, vector control cells and high HER2 cells were treated with 10 μM of PEITC for 24 h and apoptosis was estimated using ELISA cell death assay by measuring histone associated DNA fragments. (C) MDA-MB-231 (HH) cells were treated with different concentrations of PEITC for 24 h, and the whole cell lysates were analyzed by western blotting. (D) MDA-MB-231 (HH) cells were treated with PEITC for 24, 48 and 72 h with increasing concentrations of PEITC and cell survival was measured by sulforhodamine B assay. The figures are representative of at least three independent experiments with eight replicates. *Statistically different compared with control (P < 0.05).