Figure 2. Graphical representation of IC₅₀ values of Prestwick Library Hits in MCF7-Casp3 and MCF7-Bcl2.

MCF7-Casp3 and MCF7-Bcl2 cells were exposed to the 51 compound selected in the primary screen. Cells were treated with 8 different concentrations for 24hs and cell death was measured with the HT PI Cytotoxicity Assay. The percentage of dead cells was plotted with GraphPad Prism 5.0 to calculate the LC₅₀ values. Top-left panel. Graphic representation of the calculated LC₅₀ for each compound on both cell lines. The solid black line correspond to an artificial line with slope = 1 representing the ideal situation where the LC₅₀ is identical on both cell lines. Green dots = LC₅₀ for siramesine calculated form 9 concertation-response curves distributed across the screen plates, blue dots = LC₅₀ for staurosporine, black dots = LC₅₀ for Prestwick library Hits, red dots= LC₅₀ for Prestwick library Hits for which concertation-response curves are showed in the middle and bottom panels. The similar LC₅₀ in both cell lines suggest that cell death induced by most of this compound is indeed Casp3 independent (see also Figure S3). The top-right panel. Concertation-response curves for siramesine (average of 9 curves) and staurosporine. LC₅₀ ± 95% CI are shown. LC₅₀ values for siramesine in both cell lines were compared with an F-test and show no significant difference (p-value = 0.48). Middle and bottom panel. Concertation-response curves for representative compound. LC₅₀ ± 95% CI are shown. F-test and show no significant difference (p-value = > 0.05). The curves for the other compounds are shown in Figure S2.