CD44 and neoplasm: The IC50 values of KPT6566 for inhibiting cell growth were 5.76 μM for CD44+CD133+ tumor-initiating Caco-2 cells and 5.39 μM for ΔCD44+CD133+ non-tumor-initiating Caco-2 cells (Figure 5L), suggesting KPT6566 as another small-molecule compound targeting CD44+CD133+ cells.