Effect of Siah1 on SKBR3 and MCF-7 cell viability. Metabolic activity was assessed by WST assay on SKBR3 cells transfected with indicated plasmids and escalating doses of IR (0, 4 and 8 Gy) as well as in MCF-7 cells after siRNA for Siah1. A: Cell viability was significantly reduced upon Siah1 and Siah1L transfection, both in irradiated and control cells. The WST assay was done 24 h after IR and normalized to unirradiated control. Lines, mean of three independent experiments; bars, SD; *, P < 0.05. B; Siah1 siRNA potently increased cell viability in MCF-7 cells at the different time points tested. Columns, mean of three independent experiments; bars, SD; *, Siah1 siRNA vs. both untreated and control siRNA, P < 0.05.