GSK3B and neoplasm: In contrast, the addition of a suboptimal concentration of the GSK-3 inhibitor SB415286 had more moderate effects on IC50 concentration of GSK-3 inhibitor tideglusib in both MCF-7 + pLXSN (1.6×↓) and MCF-7 + KD-GSK-3β (2.4×↑) cells but it did increase the tideglusib IC50 in MCF-7 + WT-GSK-3β cells 19.4-fold indicating that GSK-3 was playing a tumor suppressor role in these cells, and suppression of its activity increased therapeutic resistance (Figure 20, Table 3).