In vitro activity: Skp2 inhibitor C1 treatment of MCF-7 breast cancer cells lines does not increase, but rather decrease the percentage of cells in G1 while increasing the G2/M population. T47D cells treated with C1 (5 μM for 16 hours) displayed an increase in G1 phase (p < 0.0001) and a decrease in S phase (p < 0.0001), correlating with p27 protein induction. In contrast, MCF-7 cells responded to C1 with a significant reduction in G1 phase (35%, p < 0.0001) and an increase in G2-M phase (43%, p < 0.0001). This G1 reduction and G2/M arrest is dose dependent on C1 (Figure 5C right; p < 0.001 and p < 0.01, respectively) and correlates with increased p27 protein levels.

Kinase Assay: Skp2 inhibitor C1 treatment of MCF-7 breast cancer cells lines does not increase, but rather decrease the percentage of cells in G1 while increasing the G2/M population. T47D cells treated with C1 (5 μM for 16 hours) displayed an increase in G1 phase (p < 0.0001) and a decrease in S phase (p < 0.0001), correlating with p27 protein induction. In contrast, MCF-7 cells responded to C1 with a significant reduction in G1 phase (35%, p < 0.0001) and an increase in G2-M phase (43%, p < 0.0001). This G1 reduction and G2/M arrest is dose dependent on C1 (Figure 5C right; p < 0.001 and p < 0.01, respectively) and correlates with increased p27 protein levels.

Cell Assay: 501 Mel cell lines are pretreated with each inhibitor (10 μM) or 0.1% DMSO (vehicle) for 16 h. Cycloheximide half-life is examined. T47D cells treated with C1 (5 μM for 16 hours) displayed an increase in G1 phase (p < 0.0001) and a decrease in S phase (p < 0.0001), correlating with p27 protein induction. In contrast, MCF-7 cells responded to C1 with a significant reduction in G1 phase (35%, p < 0.0001) and an increase in G2-M phase (43%, p < 0.0001). This G1 reduction and G2/M arrest is dose dependent on C1 (Figure 5C right; p < 0.001 and p < 0.01, respectively) and correlates with increased p27 protein levels (Figure 5E left, S4A top right.