Gamma‐secretase inhibitor IX inhibits the growth of CD44+ cancer stem cells xenograft tumors via attenuation of Notch and wnt‐beta‐catenin signaling. (A): Immunoblot showing the expression of CD44, hairy enhancer of split‐1 (Hes1), wnt 5a/b, Erk, p‐Erk, Akt, p‐Akt, Stat3, p‐stat3, and beta‐catenin of treated xenograft tumors like indicated. (B): Immunoblots showing the expression of Notch1, PARP, Rac1, Axin 2, APC, LPR6, c‐Myc, E‐cadherin, and N‐cadherin of treated xenograft tumors like indicated. Actin was used as a loading control. (C): Bar graph showing the double positive cells (Hes1+ and CD44+) from the blood of normal compared to gastric cancer patients like indicated. (D): Bar graph showing the double positive cells (Hes1+ and CD44+) from the blood of mice like indicated. **p < .005, ***p < .001. Abbreviations: Hes1, hairy enhancer of split‐1; GC, gastric cancer, MNC, mononuclear cells, NICD, Notch intracellular domain.