Figure 1.

Cellular effects mediated by indirubins. By direct inhibition of CDKs and GSK-3β and by the activation of AhR-mediated upregulation of cell cycle inhibitor p27^Kip1, indirubins inhibit cell cycle progression. They also suppress cell survival by inducing caspase-mediated apoptosis upon interfering with mitochondrial function and affecting Src and STAT-mediated expression of cell survival proteins. Furthermore, by inhibiting GP indirubins suppress glycogenolysis, thus hampering the glucose supply of cancer cells. These effects lead to inhibition of cell cycle progression and induction of cell death (→ activation/release; ⊥ inhibition).