MELK and cancer: Since MDA-MB-231 cells have an undifferentiated, cancer stem-like characteristics [20, 21], we examined the expression level of one of cancer stem cell markers, Slug (also known as Snail2), in OTS167-treated cells by western blot analysis, and found that Slug protein level was reduced with OTS167 treatment in a dose-dependent manner as similar to the MELK and DEPDC1 reduction (Figure 2C).