ZSP inhibits Notch signaling and cancer stem-like marker expression in DAOY and U87 cells. Transcript levels of the Notch1 receptor remain unchanged (A and B) while those of Notch2 receptor were down-regulated following ZSP treatment in DAOY (C) and U87 (D) cells. Hes1, a Notch downstream target, also showed dose-dependent reductions (E and F). In addition, transcript levels of stem-like cancer markers, Nestin and CD133, also demonstrated statistical significant reductions at higher concentrations (G–J). HPRT: hypo-xanthine phosphoribosyltransferase. *p≤0.05, **p≤0.01 and ***p≤0.0001 relative to the mock-treated control.